From: owner-utah-astronomy-digest@lists.xmission.com (utah-astronomy-digest) To: utah-astronomy-digest@lists.xmission.com Subject: utah-astronomy-digest V1 #59 Reply-To: utah-astronomy-digest Sender: owner-utah-astronomy-digest@lists.xmission.com Errors-To: owner-utah-astronomy-digest@lists.xmission.com Precedence: bulk utah-astronomy-digest Monday, October 8 2001 Volume 01 : Number 059 ---------------------------------------------------------------------- Date: Sat, 6 Oct 2001 21:49:08 -0600 From: "Gary Liptrot" Subject: RE: (utah-astronomy) Date: Fri, 5 Oct 2001 20:02:11 -0600 This is a multi-part message in MIME format. - ------=_NextPart_000_0007_01C14EB0.BA12F620 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8bit Hey Larry, I was waiting for someone brainy to answer this but I guess you're stuck with me. Solution #1 - move south of the equator and maybe the coriolis force will make it circulate correctly. Good excuse to see the southern skies too. Solution #2 - Ask Brent Watson. I heard that he had the same problem with his airplane propeller when he first got his plane. He flew backwards for a week before he figured out what was wrong. Solution #3 - In all (some) seriousness, sometimes when I try to figure something out that is "intuitively obvious" my mind somehow skips over the "easy" stuff that is the meat of the problem. I would experiment since there are only four bolts holding it on. Turn it around and check it again. If it still blows air backwards then goto solution #4. Solution #4 - Maybe the air is so restricted where you have mounted your fan that it just can't force air where you planned for it to go. You may be feeling the back pressure from the effort of the fan trying to blow through a too small of aperature. The fix here is a better mounting location. Just kicking around some ideas. I've seen your scope and it looks good. Got to look through it one of these days. 73 es let me know how it turns out de n7zi Gary Liptrot -----Original Message----- From: owner-utah-astronomy@lists.xmission.com [mailto:owner-utah-astronomy@lists.xmission.com]On Behalf Of Larry Frisk Sent: Friday, October 05, 2001 8:00 PM To: Utah-Astronomy@Lists.Xmission.Com Subject: (utah-astronomy) Date: Fri, 5 Oct 2001 20:02:11 -0600 Here is a problem for the brainy bunch. I was very interested by the discussion that Chuck and Brent were having a few months ago concerning the use of normalizing fans in telescope tubes. I sided with Brent and decided that I wanted my fan to draw air from the top of the tube and exhaust at the bottom to avoid picking up dust from the ground. Although I really don’t think it makes much difference because the amount of airflow is very slight and the mirror probably collects more dust in storage than in actual use. I am using a 4" fan that came out of a computer power supply. The scope is constructed from a 12" diameter Sonotube and is 64" long. The mirror cell is at the very bottom of the tube and there is about .250 space between the 10"mirror and the fan. It is pretty obvious from looking at the blade pitch and direction of rotation which direction the air will flow. I also bench tested the fan just to make sure which direction to mount the fan. However, to my amazement, the airflow is backwards. It actually draws air in from the back and exhausts out the top. Can any of you explain to me what is happening and why? BTW I really enjoy reading the comments, interesting ideas, and issues that all of you write about. _\\|//_ (-O-O-) -----o00--(_)--00o----- Larry & Kaye Frisk lkfrisk@earthlink.net - ------=_NextPart_000_0007_01C14EB0.BA12F620 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Hey=20 Larry, I was waiting for someone brainy to answer this but I guess = you're=20 stuck with me.

Solution #1 - move south of the equator and maybe the coriolis = force will=20 make it circulate correctly. Good excuse to see the southern skies = too.

Solution #2 - Ask Brent Watson. I heard that he had the = same=20 problem with his airplane propeller when he first got his plane. = He flew=20 backwards for a week before he figured out what was = wrong.

Solution #3 - In all (some) seriousness, sometimes when I try = to figure=20 something out that is "intuitively obvious" my mind somehow skips over = the=20 "easy" stuff that is the meat of the problem. I would experiment = since=20 there are only four bolts holding it on. Turn it around and check = it=20 again. If it still blows air backwards then goto solution=20 #4.

Solution #4 - Maybe the air is so restricted where you have = mounted your=20 fan that it just can't force air where you planned for it to = go. You=20 may be feeling the back pressure from the effort of the fan trying to = blow=20 through a too small of aperature. The fix here is a better = mounting=20 location.

Just=20 kicking around some ideas. I've seen your scope and it looks = good. =20 Got to look through it one of these days.

73 es=20 let me know how it turns out de n7zi

Gary=20 Liptrot

-----Original Message-----
From:=20 owner-utah-astronomy@lists.xmission.com=20 [mailto:owner-utah-astronomy@lists.xmission.com]On Behalf Of = Larry=20 Frisk
Sent: Friday, October 05, 2001 8:00 PM
To:=20 Utah-Astronomy@Lists.Xmission.Com
Subject: (utah-astronomy) = Date:=20 Fri, 5 Oct 2001 20:02:11 -0600

=20
Here is a problem for the brainy bunch.

I was very interested by the discussion that Chuck and Brent were = having a=20 few months ago concerning the use of normalizing fans in telescope = tubes.

I sided with Brent and decided that I wanted my fan to draw air = from the=20 top of the tube and exhaust at the bottom to avoid picking up dust = from the=20 ground. Although I really don=92t think it makes much difference = because the=20 amount of airflow is very slight and the mirror probably collects more = dust in=20 storage than in actual use.

I am using a 4" fan that came out of a computer power supply. The = scope is=20 constructed from a 12" diameter Sonotube and is 64" long. The mirror = cell is=20 at the very bottom of the tube and there is about .250 space between = the=20 10"mirror and the fan.

It is pretty obvious from looking at the blade pitch and direction = of=20 rotation which direction the air will flow. I also bench tested the = fan just=20 to make sure which direction to mount the fan.

However, to my amazement, the airflow is backwards. It actually = draws air=20 in from the back and exhausts out the top.

Can any of you explain to me what is happening and why?

BTW I really enjoy reading the comments, interesting ideas, and = issues that=20 all of you write about.

    =20      =20 _\\|//_
         =20 (-O-O-)
-----o00--(_)--00o-----
   Larry & Kaye=20 Frisk
lkfrisk@earthlink.net=20

- ------=_NextPart_000_0007_01C14EB0.BA12F620-- - - Visit the Utah Astronomy Message Board: http://pub61.ezboard.com/butahastronomy To unsubscribe from utah-astronomy, send an email to "majordomo@xmission.com" with "unsubscribe utah-astronomy" in the body of the message. ------------------------------ Date: Sun, 7 Oct 2001 21:04:39 -0600 From: "Larry Frisk" Subject: Re: (utah-astronomy) Date: Fri, 5 Oct 2001 20:02:11 -0600 This is a multi-part message in MIME format. - ------=_NextPart_000_002D_01C14F73.AD839680 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hello Gary, I suspect that your solution #4 is not far off the mark. However this = would be easier for me to understand if the fan was blowing toward the = back of the mirror and then bouncing back. ?? I'll play around with it a = little just to satisfy my curiosity but it's no big deal which way the = wind blows.=20 Thanks for your suggestions though. Larry ----- Original Message -----=20 From: Gary Liptrot=20 To: utah-astronomy@lists.xmission.com=20 Sent: Saturday, October 06, 2001 9:49 PM Subject: RE: (utah-astronomy) Date: Fri, 5 Oct 2001 20:02:11 -0600 Hey Larry, I=20 Solution #4 - Maybe the air is so restricted where you have mounted = your fan that it just can't force air where you planned for it to go. = You may be feeling the back pressure from the effort of the fan trying = to blow through a too small of aperature. The fix here is a better = mounting location. Gary Liptrot -----Original Message----- From: owner-utah-astronomy@lists.xmission.com = [mailto:owner-utah-astronomy@lists.xmission.com]On Behalf Of Larry Frisk Sent: Friday, October 05, 2001 8:00 PM To: Utah-Astronomy@Lists.Xmission.Com Subject: (utah-astronomy) Date: Fri, 5 Oct 2001 20:02:11 -0600 =20 Here is a problem for the brainy bunch. I was very interested by the discussion that Chuck and Brent were = having a few months ago concerning the use of normalizing fans in = telescope tubes.=20 I sided with Brent and decided that I wanted my fan to draw air from = the top of the tube and exhaust at the bottom to avoid picking up dust = from the ground. Although I really don't think it makes much difference = because the amount of airflow is very slight and the mirror probably = collects more dust in storage than in actual use. I am using a 4" fan that came out of a computer power supply. The = scope is constructed from a 12" diameter Sonotube and is 64" long. The = mirror cell is at the very bottom of the tube and there is about .250 = space between the 10"mirror and the fan. It is pretty obvious from looking at the blade pitch and direction = of rotation which direction the air will flow. I also bench tested the = fan just to make sure which direction to mount the fan. However, to my amazement, the airflow is backwards. It actually = draws air in from the back and exhausts out the top. Can any of you explain to me what is happening and why? BTW I really enjoy reading the comments, interesting ideas, and = issues that all of you write about. _\\|//_ (-O-O-) -----o00--(_)--00o----- Larry & Kaye Frisk lkfrisk@earthlink.net=20 - ------=_NextPart_000_002D_01C14F73.AD839680 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Hello Gary,

I suspect that your solution #4 is not far off the mark. However this = would=20 be easier for me to understand if the fan was blowing toward the back of = the=20 mirror and then bouncing back. ?? I’ll play around with it a = little just to=20 satisfy my curiosity but it’s no big deal which way the wind = blows.

Thanks for your suggestions though.

Larry

----- Original Message -----
From:=20 Gary = Liptrot
To: utah-astronomy@lists.xm= ission.com=20

Sent: Saturday, October 06, = 2001 9:49=20 PM

Subject: RE: (utah-astronomy) = Date: Fri,=20 5 Oct 2001 20:02:11 -0600

Hey=20 Larry, I

Solution #4 - Maybe the air is so restricted where you have = mounted=20 your fan that it just can't force air where you planned for it to = go. You may be feeling the back pressure from the effort of the = fan=20 trying to blow through a too small of aperature. The fix here is = a=20 better mounting location.

Gary=20 Liptrot

-----Original Message-----
From:=20 owner-utah-astronomy@lists.xmission.com=20 [mailto:owner-utah-astronomy@lists.xmission.com]On Behalf Of = Larry=20 Frisk
Sent: Friday, October 05, 2001 8:00 PM
To: = Utah-Astronomy@Lists.Xmission.Com
Subject: = (utah-astronomy) Date:=20 Fri, 5 Oct 2001 20:02:11 -0600

=20
Here is a problem for the brainy bunch.

I was very interested by the discussion that Chuck and Brent were = having=20 a few months ago concerning the use of normalizing fans in telescope = tubes.=20

I sided with Brent and decided that I wanted my fan to draw air = from the=20 top of the tube and exhaust at the bottom to avoid picking up dust = from the=20 ground. Although I really don’t think it makes much difference = because the=20 amount of airflow is very slight and the mirror probably collects = more dust=20 in storage than in actual use.

I am using a 4" fan that came out of a computer power supply. The = scope=20 is constructed from a 12" diameter Sonotube and is 64" long. The = mirror cell=20 is at the very bottom of the tube and there is about .250 space = between the=20 10"mirror and the fan.

It is pretty obvious from looking at the blade pitch and = direction of=20 rotation which direction the air will flow. I also bench tested the = fan just=20 to make sure which direction to mount the fan.

However, to my amazement, the airflow is backwards. It actually = draws air=20 in from the back and exhausts out the top.

Can any of you explain to me what is happening and why?

BTW I really enjoy reading the comments, interesting ideas, and = issues=20 that all of you write about.

    =20      =20 _\\|//_
         =20 (-O-O-)
-----o00--(_)--00o-----
   Larry & Kaye=20 Frisk
lkfrisk@earthlink.net=20

- ------=_NextPart_000_002D_01C14F73.AD839680-- - - Visit the Utah Astronomy Message Board: http://pub61.ezboard.com/butahastronomy To unsubscribe from utah-astronomy, send an email to "majordomo@xmission.com" with "unsubscribe utah-astronomy" in the body of the message. ------------------------------ Date: Mon, 8 Oct 2001 07:30:57 -0700 (PDT) From: Chuck Hards Subject: (utah-astronomy) Baffling a Newtonian Someone asked me recently about baffling a Newtonian, and I must confess that I can't locate the folder where I archived the message, so I don't know who it was! (The "Senior Moments" are becomming more frequent....) Anyway, the article I referred to is in the September 96 issue of Astronomy magazine (one of the 12 issues I've kept of their entire press run from day 1). Chuck __________________________________________________ Do You Yahoo!? NEW from Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month. http://geocities.yahoo.com/ps/info1 - - Visit the Utah Astronomy Message Board: http://pub61.ezboard.com/butahastronomy To unsubscribe from utah-astronomy, send an email to "majordomo@xmission.com" with "unsubscribe utah-astronomy" in the body of the message. ------------------------------ Date: Mon, 8 Oct 2001 07:53:22 -0700 (PDT) From: Chuck Hards Subject: (utah-astronomy) Aurora monitor While looking through some old magazines this past weekend, I found a neat device for detecting auroral activity. It is essentially a bar magnet suspended by a thread, inside a clear glass jar (to remove air current effects) with a light source focused on a reflective area. When the magnet moves, due to changes in the earth's magnetic field, the light beam is deflected slightly. The amount of deflection can be calibrated to show the approximate level of disturbance to the earth's magnetic field. It's called the "$3 Aurora monitor". If there is any interest, I'll look up the details again this week, and post them, but I'm sure most list members grasp this concept instantly, and could build one from my description alone. Chuck __________________________________________________ Do You Yahoo!? NEW from Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month. http://geocities.yahoo.com/ps/info1 - - Visit the Utah Astronomy Message Board: http://pub61.ezboard.com/butahastronomy To unsubscribe from utah-astronomy, send an email to "majordomo@xmission.com" with "unsubscribe utah-astronomy" in the body of the message. ------------------------------ Date: Mon, 8 Oct 2001 08:02:46 -0700 (PDT) From: Chuck Hards Subject: (utah-astronomy) Fans Someone posted to the effect that they wanted to install a fan, and chose a configuration based on the logic of a personal choice. If you want your installation to have a positive effect, try and ascertain first what the precise nature of the problem is. Is it tube currents? Local seeing effects from the ground around you? Temperature-sensitive astigmatism? Mirror cool-down taking too long? Lack of clearance between the edge of the mirror and tube wall? The real problem will dictate the best solution. Currently in vogue as a "catch-all" fan installation is the sideways-blowing mounting. Air is sucked in from the side of the tube, blown across it's face, and then out the opposite side of the tube. I'm not really on-board with this as a universal cure. It doesn't address tube currents occurring higher up in the optical path at all, and can cause internal eddies. It will remove a boundary-layer that is out-of-equilibrium, however. For any Newtonian over 6", though, I do advise a fan. The 37" is getting 3 fans mounted behind the mirror, blowing into the tube directly onto the back of the mirror, mounted on Sorbothane with Nylon screws. Chuck __________________________________________________ Do You Yahoo!? NEW from Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month. http://geocities.yahoo.com/ps/info1 - - Visit the Utah Astronomy Message Board: http://pub61.ezboard.com/butahastronomy To unsubscribe from utah-astronomy, send an email to "majordomo@xmission.com" with "unsubscribe utah-astronomy" in the body of the message. ------------------------------ Date: Mon, 8 Oct 2001 08:10:34 -0700 (PDT) From: Jim Stitley Subject: Re: (utah-astronomy) Aurora monitor Sounds very interesting - would like more info on magnetb type to make one and how you note the degree of deflection - - a scale??? Thanks - neat idea. Jim Stitley - --- Chuck Hards wrote: > While looking through some old magazines this past > weekend, I found a neat device for detecting auroral > activity. It is essentially a bar magnet suspended by > a thread, inside a clear glass jar (to remove air > current effects) with a light source focused on a > reflective area. When the magnet moves, due to > changes in the earth's magnetic field, the light beam > is deflected slightly. The amount of deflection can > be calibrated to show the approximate level of > disturbance to the earth's magnetic field. > > It's called the "$3 Aurora monitor". > > If there is any interest, I'll look up the details > again this week, and post them, but I'm sure most list > members grasp this concept instantly, and could build > one from my description alone. > > Chuck > > __________________________________________________ > Do You Yahoo!? > NEW from Yahoo! GeoCities - quick and easy web site > hosting, just $8.95/month. > http://geocities.yahoo.com/ps/info1 > > - > Visit the Utah Astronomy Message Board: > http://pub61.ezboard.com/butahastronomy > To unsubscribe from utah-astronomy, send an email to > "majordomo@xmission.com" > with "unsubscribe utah-astronomy" in the body of the message. __________________________________________________ Do You Yahoo!? NEW from Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month. http://geocities.yahoo.com/ps/info1 - - Visit the Utah Astronomy Message Board: http://pub61.ezboard.com/butahastronomy To unsubscribe from utah-astronomy, send an email to "majordomo@xmission.com" with "unsubscribe utah-astronomy" in the body of the message. ------------------------------ Date: Mon, 8 Oct 2001 08:22:07 -0700 (PDT) From: Chuck Hards Subject: Re: (utah-astronomy) Aurora monitor Jim, I'm pretty sure it was in an S & T issue, maybe ten to fifteen years old. I picked up some old copies from Patrick last Thursday, and it may have been in one of those. I'll look it up tonight. You are on the exact righ track. The author used a ruler to project the deflected light beam onto, to make readings easier to interpret. These days, one may be able to use a pocket laser pointer instead of a flashlight, and project the deflected beam across the room. The longer the distance, the greater the linear deflection, hence better visibility. My only concern is random "noise". The jiggles associated with auroral activity could be lost to noise unless the jar is mounted with forethought, maybe on a sorbothane "coaster".... Chuck - --- Jim Stitley wrote: > Sounds very interesting - would like more info on > magnetb > type to make one and how you note the degree of > deflection > - a scale??? Thanks - neat idea. > Jim Stitley > --- Chuck Hards wrote: > > While looking through some old magazines this past > > weekend, I found a neat device for detecting > auroral > > activity. It is essentially a bar magnet > suspended by > > a thread, inside a clear glass jar (to remove air > > current effects) with a light source focused on a > > reflective area. When the magnet moves, due to > > changes in the earth's magnetic field, the light > beam > > is deflected slightly. The amount of deflection > can > > be calibrated to show the approximate level of > > disturbance to the earth's magnetic field. > > > > It's called the "$3 Aurora monitor". > > > > If there is any interest, I'll look up the details > > again this week, and post them, but I'm sure most > list > > members grasp this concept instantly, and could > build > > one from my description alone. > > > > Chuck > > > > __________________________________________________ > > Do You Yahoo!? > > NEW from Yahoo! GeoCities - quick and easy web > site > > hosting, just $8.95/month. > > http://geocities.yahoo.com/ps/info1 > > > > - > > Visit the Utah Astronomy Message Board: > > http://pub61.ezboard.com/butahastronomy > > To unsubscribe from utah-astronomy, send an email > to > > "majordomo@xmission.com" > > with "unsubscribe utah-astronomy" in the body of > the > message. > > > __________________________________________________ > Do You Yahoo!? > NEW from Yahoo! GeoCities - quick and easy web site > hosting, just $8.95/month. > http://geocities.yahoo.com/ps/info1 > > - > Visit the Utah Astronomy Message Board: > http://pub61.ezboard.com/butahastronomy > To unsubscribe from utah-astronomy, send an email > to "majordomo@xmission.com" > with "unsubscribe utah-astronomy" in the body of > the message. __________________________________________________ Do You Yahoo!? NEW from Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month. http://geocities.yahoo.com/ps/info1 - - Visit the Utah Astronomy Message Board: http://pub61.ezboard.com/butahastronomy To unsubscribe from utah-astronomy, send an email to "majordomo@xmission.com" with "unsubscribe utah-astronomy" in the body of the message. ------------------------------ Date: Mon, 8 Oct 2001 08:35:06 -0700 (PDT) From: Jim Stitley Subject: Re: (utah-astronomy) Aurora monitor Chuck, I believe the Chem Shop on north Redwood Road (don't know address off top of my head) that sells all types of home lab supplies , sells Bell Jars I believe - usually used to cover microscopes. Also, some hobby & craftshops sell things like bell jars to display "neat stuff" under glass. That might be what I would use to dampen air currents. Would a pocket laser pointer be too heavy for the magnet and inhibit turning? What type of magnet was recommended? If not, that is a neat idea - can see it now - a 6 foot grid on one living room wall, and the bell jar on the opposite wall - hhhmmm, new (functional) home art? Jim Stitley - --- Chuck Hards wrote: > Jim, I'm pretty sure it was in an S & T issue, maybe > ten to fifteen years old. I picked up some old copies > from Patrick last Thursday, and it may have been in > one of those. I'll look it up tonight. > > You are on the exact righ track. The author used a > ruler to project the deflected light beam onto, to > make readings easier to interpret. > > These days, one may be able to use a pocket laser > pointer instead of a flashlight, and project the > deflected beam across the room. The longer the > distance, the greater the linear deflection, hence > better visibility. > > My only concern is random "noise". The jiggles > associated with auroral activity could be lost to > noise unless the jar is mounted with forethought, > maybe on a sorbothane "coaster".... > > Chuck > > > --- Jim Stitley wrote: > > Sounds very interesting - would like more info on > > magnetb > > type to make one and how you note the degree of > > deflection > > - a scale??? Thanks - neat idea. > > Jim Stitley > > --- Chuck Hards wrote: > > > While looking through some old magazines this past > > > weekend, I found a neat device for detecting > > auroral > > > activity. It is essentially a bar magnet > > suspended by > > > a thread, inside a clear glass jar (to remove air > > > current effects) with a light source focused on a > > > reflective area. When the magnet moves, due to > > > changes in the earth's magnetic field, the light > > beam > > > is deflected slightly. The amount of deflection > > can > > > be calibrated to show the approximate level of > > > disturbance to the earth's magnetic field. > > > > > > It's called the "$3 Aurora monitor". > > > > > > If there is any interest, I'll look up the details > > > again this week, and post them, but I'm sure most > > list > > > members grasp this concept instantly, and could > > build > > > one from my description alone. > > > > > > Chuck > > > > > > __________________________________________________ > > > Do You Yahoo!? > > > NEW from Yahoo! GeoCities - quick and easy web > > site > > > hosting, just $8.95/month. > > > http://geocities.yahoo.com/ps/info1 > > > > > > - > > > Visit the Utah Astronomy Message Board: > > > http://pub61.ezboard.com/butahastronomy > > > To unsubscribe from utah-astronomy, send an email > > to > > > "majordomo@xmission.com" > > > with "unsubscribe utah-astronomy" in the body of > > the > > message. > > > > > > __________________________________________________ > > Do You Yahoo!? > > NEW from Yahoo! GeoCities - quick and easy web site > > hosting, just $8.95/month. > > http://geocities.yahoo.com/ps/info1 > > > > - > > Visit the Utah Astronomy Message Board: > > http://pub61.ezboard.com/butahastronomy > > To unsubscribe from utah-astronomy, send an email > > to "majordomo@xmission.com" > > with "unsubscribe utah-astronomy" in the body of > > the message. > > > __________________________________________________ > Do You Yahoo!? > NEW from Yahoo! GeoCities - quick and easy web site > hosting, just $8.95/month. > http://geocities.yahoo.com/ps/info1 > > - > Visit the Utah Astronomy Message Board: > http://pub61.ezboard.com/butahastronomy > To unsubscribe from utah-astronomy, send an email to > "majordomo@xmission.com" > with "unsubscribe utah-astronomy" in the body of the message. __________________________________________________ Do You Yahoo!? NEW from Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month. http://geocities.yahoo.com/ps/info1 - - Visit the Utah Astronomy Message Board: http://pub61.ezboard.com/butahastronomy To unsubscribe from utah-astronomy, send an email to "majordomo@xmission.com" with "unsubscribe utah-astronomy" in the body of the message. ------------------------------ Date: Mon, 8 Oct 2001 08:51:30 -0700 (PDT) From: Chuck Hards Subject: Re: (utah-astronomy) Aurora monitor The light source isn't carried by the string. The magnet has a small mirror attached to it. The light source and screen (or grid) are on the exterior of the jar. The one in the article used a Mason jar, but a bell jar or flask would definitely make it look more 'scientific'! A light-detecting circuit with a photocell could be substituted for the grid/ruler, maybe giving increased sensitivity. The Chem Shop is still there on Redwood road, somewhere between 8th and 12th south. Chuck - --- Jim Stitley wrote: > Chuck, > I believe the Chem Shop on north Redwood Road (don't > know > address off top of my head) that sells all types of > home > lab supplies , sells Bell Jars I believe - usually > used to > cover microscopes. Also, some hobby & craftshops > sell > things like bell jars to display "neat stuff" under > glass. > That might be what I would use to dampen air > currents. > Would a pocket laser pointer be too heavy for the > magnet > and inhibit turning? What type of magnet was > recommended? > If not, that is a neat idea - can see it now - a 6 > foot > grid on one living room wall, and the bell jar on > the > opposite wall - hhhmmm, new (functional) home art? > Jim Stitley > > --- Chuck Hards wrote: > > Jim, I'm pretty sure it was in an S & T issue, > maybe > > ten to fifteen years old. I picked up some old > copies > > from Patrick last Thursday, and it may have been > in > > one of those. I'll look it up tonight. > > > > You are on the exact righ track. The author used > a > > ruler to project the deflected light beam onto, to > > make readings easier to interpret. > > > > These days, one may be able to use a pocket laser > > pointer instead of a flashlight, and project the > > deflected beam across the room. The longer the > > distance, the greater the linear deflection, hence > > better visibility. > > > > My only concern is random "noise". The jiggles > > associated with auroral activity could be lost to > > noise unless the jar is mounted with forethought, > > maybe on a sorbothane "coaster".... > > > > Chuck > > > > > > --- Jim Stitley wrote: > > > Sounds very interesting - would like more info > on > > > magnetb > > > type to make one and how you note the degree of > > > deflection > > > - a scale??? Thanks - neat idea. > > > Jim Stitley > > > --- Chuck Hards wrote: > > > > While looking through some old magazines this > past > > > > weekend, I found a neat device for detecting > > > auroral > > > > activity. It is essentially a bar magnet > > > suspended by > > > > a thread, inside a clear glass jar (to remove > air > > > > current effects) with a light source focused > on a > > > > reflective area. When the magnet moves, due > to > > > > changes in the earth's magnetic field, the > light > > > beam > > > > is deflected slightly. The amount of > deflection > > > can > > > > be calibrated to show the approximate level of > > > > disturbance to the earth's magnetic field. > > > > > > > > It's called the "$3 Aurora monitor". > > > > > > > > If there is any interest, I'll look up the > details > > > > again this week, and post them, but I'm sure > most > > > list > > > > members grasp this concept instantly, and > could > > > build > > > > one from my description alone. > > > > > > > > Chuck > > > > > > > > > __________________________________________________ > > > > Do You Yahoo!? > > > > NEW from Yahoo! GeoCities - quick and easy web > > > site > > > > hosting, just $8.95/month. > > > > http://geocities.yahoo.com/ps/info1 > > > > > > > > - > > > > Visit the Utah Astronomy Message Board: > > > > http://pub61.ezboard.com/butahastronomy > > > > To unsubscribe from utah-astronomy, send an > email > > > to > > > > "majordomo@xmission.com" > > > > with "unsubscribe utah-astronomy" in the body > of > > > the > > > message. > > > > > > > > > > __________________________________________________ > > > Do You Yahoo!? > > > NEW from Yahoo! GeoCities - quick and easy web > site > > > hosting, just $8.95/month. > > > http://geocities.yahoo.com/ps/info1 > > > > > > - > > > Visit the Utah Astronomy Message Board: > > > http://pub61.ezboard.com/butahastronomy > > > To unsubscribe from utah-astronomy, send an > email > > > to "majordomo@xmission.com" > > > with "unsubscribe utah-astronomy" in the body > of > > > the message. > > > > > > __________________________________________________ > > Do You Yahoo!? > > NEW from Yahoo! GeoCities - quick and easy web > site > > hosting, just $8.95/month. > > http://geocities.yahoo.com/ps/info1 > > > > - > > Visit the Utah Astronomy Message Board: > > http://pub61.ezboard.com/butahastronomy > > To unsubscribe from utah-astronomy, send an email > to > > "majordomo@xmission.com" > > with "unsubscribe utah-astronomy" in the body of > the > message. > > > __________________________________________________ > Do You Yahoo!? > NEW from Yahoo! GeoCities - quick and easy web site > hosting, just $8.95/month. > http://geocities.yahoo.com/ps/info1 > > - > Visit the Utah Astronomy Message Board: > http://pub61.ezboard.com/butahastronomy > To unsubscribe from utah-astronomy, send an email > to "majordomo@xmission.com" > with "unsubscribe utah-astronomy" in the body of > the message. __________________________________________________ Do You Yahoo!? NEW from Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month. http://geocities.yahoo.com/ps/info1 - - Visit the Utah Astronomy Message Board: http://pub61.ezboard.com/butahastronomy To unsubscribe from utah-astronomy, send an email to "majordomo@xmission.com" with "unsubscribe utah-astronomy" in the body of the message. ------------------------------ Date: Mon, 8 Oct 2001 10:11:41 -0700 From: "William Kelley" Subject: Re: (utah-astronomy) Fans Chuck, The fan blowing from the side is not intended to remove the boundary layer of turbulent air. It breaks the layer up into microcells of turbulence which have too short a light path to refract light enough to distort the image. Alan Adler and Brian Greer have an article in press for S&T that will describe this approach. Turning on the fan produces an instantaneous clearing of the image- even when the mirror is not in thermal equilibrium. Regards to you and all of my SLAS friends, Bill - ----- Original Message ----- From: Chuck Hards To: Sent: Monday, October 08, 2001 8:02 AM Subject: (utah-astronomy) Fans > Someone posted to the effect that they wanted to > install a fan, and chose a configuration based on the > logic of a personal choice. > > If you want your installation to have a positive > effect, try and ascertain first what the precise > nature of the problem is. Is it tube currents? Local > seeing effects from the ground around you? > Temperature-sensitive astigmatism? Mirror cool-down > taking too long? Lack of clearance between the edge > of the mirror and tube wall? > > The real problem will dictate the best solution. > > Currently in vogue as a "catch-all" fan installation > is the sideways-blowing mounting. Air is sucked in > from the side of the tube, blown across it's face, and > then out the opposite side of the tube. > > I'm not really on-board with this as a universal cure. > It doesn't address tube currents occurring higher up > in the optical path at all, and can cause internal > eddies. It will remove a boundary-layer that is > out-of-equilibrium, however. > > For any Newtonian over 6", though, I do advise a fan. > > The 37" is getting 3 fans mounted behind the mirror, > blowing into the tube directly onto the back of the > mirror, mounted on Sorbothane with Nylon screws. > > > Chuck > > __________________________________________________ > Do You Yahoo!? > NEW from Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month. > http://geocities.yahoo.com/ps/info1 > > - > Visit the Utah Astronomy Message Board: > http://pub61.ezboard.com/butahastronomy > To unsubscribe from utah-astronomy, send an email to "majordomo@xmission.com" > with "unsubscribe utah-astronomy" in the body of the message. > - - Visit the Utah Astronomy Message Board: http://pub61.ezboard.com/butahastronomy To unsubscribe from utah-astronomy, send an email to "majordomo@xmission.com" with "unsubscribe utah-astronomy" in the body of the message. ------------------------------ End of utah-astronomy-digest V1 #59 *********************************** - To unsubscribe to $LIST, send an email to "majordomo@xmission.com" with "unsubscribe $LIST" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.