June 2008 - Utah-Astronomy - mailman.xmission.com

Ealing target locating and index error wheel
by Canopus56 16 Jun '08

16 Jun '08

Earlier today I posted links to a series of gallery pics and schematics for a 2 inch double targeting setup for use on the Ealing. This post explains the optional "index error wheel" shown those pics. The index error wheel (my term) is a cheap substitute for a reticule and acts as an aid to center a target in the small TFOV eyepiece or on a small camera chip. It provides a reference frame for positioning a target in a search eyepiece, adjusted for targeting error, such that the object will then appear centered on a camera chip or small focal length ep TFOV. Athough the context of the following discussion involves the Ealing and a two eyepiece search and target setup, the principle applies to imaging with a parafocal eyepiece, a flip mirror and a camera with a small chip: Ealing - visual - double targeting setup - 2 inch version http://gallery.utahastronomy.com/main.php?g2_itemId=11558 Ealing - visual - double targeting setup - 2 inch version - index error wheel view 2 http://gallery.utahastronomy.com/main.php?g2_itemId=11562 Whenever a flip mirror is placed in an optical train to select different optical paths, a small index error is created between the two fields-of-view. Imperfections in the manufacture of the flip mirror surface and/or its mounting will cause an object to appear at different apparent locations in the two eyepieces or in one eyepiece and camera. Simply put, an object centered in a search and targeting parafocal eyepiece will not be centered on a camera chip in the other optical path. I term this "targeting index error". On equatorial mounted scopes, the targeting index error can be addressed by using a Meade reticule with a 12mm focal length. For longer focal length scopes like the Ealing or an SCT without a focal reducer, the TFOV of a reticule eyepiece is extremely small (7 arcminutes in the Ealing and around 15 arcminutes in an SCT). That small TFOV presents a target acquisition problem in itself. With a reticule, a bright star is centered on the chip and then in the targeting parafocal eyepiece, the object's error offset from the center of the eyepiece and its position angle is noted. For further DSO targets like faint galaxies, you just put the faint fuzzy at the same location as measured in the reticule and then it will be somewhere on the camera chip. The index error wheel is a cheap alternative that performs the same function. It is something I whipped up and not something generally seen in amateur astronomical literature (although I am sure someone else already came up with it in the past). The index error wheel is simply a circular protractor that is glued to a CD or a DVD. The CD is drilled out with a 1 1/4 inch or 2 inch drill bit. Then the protractor can be trapped in place between the eyepiece and eyepiece holder. Use the index wheel like a reticule. First, you slew a star in the eyepiece back and forth using the right ascension buttons. Then rotate the protractor so a convienent 90 or 180 degree mark lines up with this line. You can pull back from the eyepiece and see both the target star and the protractor scale at the same time. It helps to use a finger to point from the protractor scale to the center of the eyepiece. You'll only need to make a rough adjustment. The protractor and eyepiece are trapped in a fixed position using the eyepiece screw. The protractor and eyepiece remain fixed in that position for the rest of your observing session and mark the right ascension and declination sight lines in your eyepiece TFOV not matter how the orientation of the eyepiece changes as the scope if slewed or meridian flopped. Second, center a bright star in the camera or small TFOV observing eyepiece. Flop your flip mirror to look through your large TFOV search ep. The target will not be centered in the ep. Note the position angle of the offset target using the index error wheel. Estimate the distance of the target from the eyepiece's center, noting that generally eyepieces have a 50 degree apparent field of view (AFOV). Third, slew to your faint fuzzy target and position the target using your search eyepiece and the index wheel. Position the faint fuzzy in the wide angle search TFOV eyepiece at the same position angle and distance from the ep's center as was measured for the bright star. Odds are, the faint fuzzy will be in your small TFOV observing eyepiece or will be seen on the camera chip. The effect of small TFOV on the level of difficulty in acquiring a target is significant. On the Ealing, a 32mm ep has a 20 arcminute TFOV. The circumference of the ep TFOV is about 63 arcminutes. If a faint 4x5 arcminute galaxy is hovering just outside the ep's field of view, your odds of finding it are not good (1 in 15). The search area covered by a larger 52mm ep is disproportionately large. The area of a circle varies by the square of its diameter. Therefore, the relative areas of two ep TFOV's is proportional to the square of their ratios. That means on the Ealing for a 52mm ep with a 32 arcminute TFOV and a 25 mm ep with a 15 arcminute ep, the ratio of the search areas is ( (32/15^2) or about 4.5 to 1. When slewing the two AFOVs around, you can see how the 52mm will quickly cover 20 times the search area of the 25mm ep. Testing the above setup on the Ealing last night under a near full Moon, I had no difficulty getting M13 centered exactly the middle of a 32mm ep with a TFOV of 20'. Using the above double search and observing eyepiece setup and the index error wheel are aids to make using the Ealing a much more enjoyable experience. I also have found it a useful kludge for centering DSO and lunar targets on a camera chip. Peace - Kurt

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Holding the Sun
by Patrick Wiggins 16 Jun '08

16 Jun '08

This showed up on the OAS list earlier today. Nice shots of folks "holding" the Sun: http://www.teennerd.com/2008/03/04/another-reason-i-love-flickr-holding-the… patrick

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Ealing visual obs and spectrograph setups - pics and schematics
by Canopus56 16 Jun '08

16 Jun '08

Ealing equipment setups and reference schematics posted to the gallery. Enjoy - Kurt ============================= I. Filter wheel load chart Handy for loading filters into a circular filter wheel. Filter wheel load chart http://gallery.utahastronomy.com/main.php?g2_itemId=11571 II. 2 inch version of double targeting and observing setup for Ealing and star parties Last week I posted a preliminary setup for a 2 inch double eyepiece setup for targeting the Ealing. Last night I tested the setup and made some revisions to make both the 2 inch eps parafocal. Ealing - visual - double targeting setup - 2 inch version http://gallery.utahastronomy.com/main.php?g2_itemId=11558 Ealing - visual - double targeting setup - 2 inch version - index error wheel http://gallery.utahastronomy.com/main.php?g2_itemId=11560 Ealing - visual - double targeting setup - 2 inch version - index error wheel view 2 http://gallery.utahastronomy.com/main.php?g2_itemId=11562 Ealing - visual - double targeting setup - 2 inch version - schematic http://gallery.utahastronomy.com/main.php?g2_itemId=11564 Ealing - visual - Mak use of index error wheel http://gallery.utahastronomy.com/main.php?g2_itemId=11566 Please disregard and discard the prior preliminary rough setup. More on "index error wheel" use in a follow-up post. A quick test on targeting M13 under a sky washed out by a near Full Moon indicated the setup works very well and quickly brings targets into the small eyepiece TFOVs (less than 20') typical of the Ealing and despite targeting and tracking errors in inherent in the Ealing. III. Schematic for visual spectroscopy observing on the Ealing A couple of weeks ago, I posted a photo of a setup for visual spectroscopy observing of bright stars using the Rainbow Optics grating on the Ealing. Here's a supplemental schematic showing the components of the setup. Ealing visual spectroscopy setup http://gallery.utahastronomy.com/main.php?g2_itemId=11449 Ealing visual spectroscopy schematic http://gallery.utahastronomy.com/main.php?g2_itemId=11579 Note for visual observing, the Rainbow Optics grating manual statest that the spectrum must be defocused slightly infocus to bring out the spectral bands. A separate eyepiece magnifier, that is a cylindrical magnifier lens sits on top of the grating stack. This is also intended to smear out the spectrum in one axis to better see the element absorption lines. (My impression was that either practice did not help much.) IV. Slitless spectrograph imaging setup for the Ealing Yesterday, I posted drift spectrographs taken with the Ealing on June 8. A couple of weeks ago, I posted a spectroscopy imaging setup. When retesting on June 8, I discovered there were some instances with Johnson filters in place that the camera did not have sufficient infocus travel to reach focus. Here is revised spectrograph setup for slitless grating spectroscopy of bright stars. This was the setup used to take the June 8 drift spectrographs: Ealing spectroscopy imaging - revised setup 20080608 http://gallery.utahastronomy.com/main.php?g2_itemId=11573 Ealing spectroscopy imaging - independently rotatable grating and camera http://gallery.utahastronomy.com/main.php?g2_itemId=11575 Ealing spectroscopy imaging - revised schematic 20080608 http://gallery.utahastronomy.com/main.php?g2_itemId=11577 Please disregard the prior setup version. A key feature of this setup is the ability to independently rotate the grating and camera. The grating is stored on the end of a shorty barlow with the lens removed. First, an eyepiece is substituted for the camera. The grating is rotating while viewing a bright star, such that the spectra falls aligned to the north-south declination line. Then the grating is fixed in place. Second, the camera is inserted behind the grating and then is rotated so the north-south aligned spectra falls on the long side of the camera's image frame. Then the camera is fixed in place and neither component is moved for the rest of the imaging session. This process simplifies finding and placing the spectra on the chip. Whenever the star's (first order) image can be found, you then just push the north declination slew button. You can be certain the spectra will shortly appear. Once the spectra is aligned on the chip, a long exposure (7-10 seconds) is taken with the right ascension drive turned off. That allows the spectra to drift across the camera image frame and making a smeared image. The smeared image better brings out the spectral lines as in - A drift strip spectrograph of Arcturus 20080608 http://gallery.utahastronomy.com/main.php?g2_itemId=11543 - Kurt

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Folding table suitable for astronomy at Walgreens
by Canopus56 16 Jun '08

16 Jun '08

I was in the Walgreens at 400 South and 500 East in SLC today. They had a stack of 19"x(2)*23"x29"(h) folding tables that seemed suitable for astronomy. Price is $25. The table folds out to 19"x46" and folds-up into a nice brief case like case that is 4" thick that would easily store in a trunk. Black vinyl surface. Made in Mexico. It's a bit low for a chart table to my taste, but is the right height to put two or three gear cases on or one gear case and some charts. - Kurt

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Re: [Utah-astronomy] DesctructiveGear.com
by Wayne Sumner 16 Jun '08

16 Jun '08

Seth, If it's still available, I'll buy it for $180, battery included. Please let me know quick. I have a star party coming up soon. Thanks, Wayne A. Sumner Math/Physics/Astronomy/Engineering Boy's Tennis Coach Northridge High School Davis School District (801) 402-8610 >>> "Seth Jarvis" <SJarvis(a)slco.org> 06/13/08 1:22 PM >>> OK, I've completely lost my mind. I just ordered the 100 mW version of the laser. That means my one-day-old-perfect-condition 75 mW (actually specs at 80) is up for sale for the $180 it cost me, but I'll throw in the $10 battery I put in it yesterday. Seth -----Original Message----- From: utah-astronomy-bounces(a)mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Seth Jarvis Sent: Friday, June 13, 2008 1:11 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] DesctructiveGear.com Nope, this will be my first report to the group. My 75mW green laser from DestructiveGear.com arrived yesterday (Thursday), less than a week after I ordered it. Considering it came in an envelope with a Taiwanese postmark, that's pretty impressive. The laser seems to be very well made and came with a bench test report indicating that over its 20 second quality control test it had a mean output of a skosh over 80 mW. This little bugger is _bright_. If you want to do the electrical tape cutting and match lighting, this laser is just _barely_ able to do that. I'd say go for the 100 mW if you're dreaming of a death ray. As a night sky pointer, it's simply incredible. As I told Chuck off-line, a person with a P.A. system and one of these lasers could do a star & constellation ID session for a very large audience. I had my son stand over a hundred feet from my last night in city lighting conditions and the beam still looked like a bright pole of light going right to the star he was pointing at. I wish I'd bought the 100 mW laser, but this little bugger for $180 is still sweet - my favorite new toy. BTW, it uses fairly expensive 123 Lithium camera batteries. The best deal I've found for them is a box of 12 from surefire.com. Delivered they'll run you about $26 for the dozen, compared to about $8-$10 each if bought singly from the local supermarket. It's a blast! Seth Jarvis, Director Clark Planetarium -----Original Message----- From: utah-astronomy-bounces(a)mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Chuck Hards Sent: Friday, June 13, 2008 12:54 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] DesctructiveGear.com I got a tracking update that my 100mw has cleared Customs. Should be here in a few days. Seth has reported terrific incendiary news on his 75mw. (Did you report to the group while I was off-line?) _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com

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Re: [Utah-astronomy] Ealing - Astro-physics Model 8002 drive
by Canopus56 16 Jun '08

16 Jun '08

Chuck wrote: > I may still actually have the original instructions. If > so, I will make a copy for the Ealing manual. Thanks. I'm sure the club members would appreciate it. After practing calibrating the controller again last night, I have made a small revision to my use notes. On both the initial rough and the later final calibration, the calibration light should be adjusted to make it go out - not hold steady. Lurkers, please disregard and replace the prior cheat sheet. The good news with calibration, the drift rate without periodic error correction (PEC) on the 40 year old mount meets the performance of a Vixen mount without PEC. - Peace Kurt ======================= Use notes on the Ealing for lurkers With drive calibration, the Skywizard still registers an index error of about 0.3 degs in RA only for a 9 deg slew on two tests (Vega to M57 and Vega to M13). That means at best the Skywizard will put a target somewhere in the Mak view, but it cannot be used for actually getting the target into a short-focal length (32-25mm) observing eyepiece. CHEAT SHEET FOR CALIBRATING THE EALING'S ASTROPHYSICS MODEL 8002 DRIVE CONTROLLER The controller uses a quartz crystal to generate a reference signal. Knobs and lights on the front of the controller, left to right, are: Calibration Light Power Mode - Sidereal, Solar, Lunar, Calibrate Calibration Knob - This is non-functioning. Set it to the middle and forget it Auto-Manual RA - Always set to manual Auto-Manual Dec - Always set to manual Plug-input for the slow motion control and also off to the side - Separate slow motion control with rate dial knob. Procedure: 1) On start-up, set the Mode to "Calibrate". 2) The Calibration Light will slowly flicker over 0.5 to 2 seconds. 3) Using the dial knob on slow motion control, turn the knob until the rate of flicker in the calibration light is minimized. Typically, it will flicker over 2-5 seconds. On start-up the crystal is cold and you will not be able to absolutely calibrate the drive rate. You can only do a rough calibration. 4) Turn the mode knob to the desired use mode, e.g. - "sidereal" or "lunar". 5) After using the scope for 30-45 minutes, the reference-signal crystal will reach operating temperature. 5) Repeat steps 1-4. This time you will be able to adjust the calibration light so it will stop flickering completely. The calibration light will adjust so it goes out. When you switch to use mode, the light will glow steady. 6) Avoid turning the dial rate knob when using the slow motion controller. I bumped it while in the middle of imaging, accidentially changed the setting, and M13 zipped right off the camera chip. Once calibrated, the drift rate for commonly observed objects will effectively disappear and the sub-arcsec drift error rate is in a zone sufficient for astrophotography. Once calibrated, the "lunar" mode also does a fair job of lunar target tracking. In lunar mode, the Ealing will track well within any limitations needed for imaging and stacking lunar images within Registax. Without drive controller calibration, DSO will drift out of an Ealing 32mm-25mm observing eyepiece in two to three minutes. ===============

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Re: [Utah-astronomy] DesctructiveGear.com
by Wayne Sumner 16 Jun '08

16 Jun '08

GREAT! I'll come by Monday between 10 am and Noon if that's OK. Cash OK?, or do you need a receipt or check for a record? Wayne A. Sumner Math/Physics/Astronomy/Engineering Boy's Tennis Coach Northridge High School Davis School District (801) 402-8610 >>> "Seth Jarvis" <SJarvis(a)slco.org> 06/15/08 1:30 PM >>> Wayne, It's yours. I'll have it at work with me beginning Monday. Thanks! Seth -----Original Message----- From: utah-astronomy-bounces(a)mailman.xmission.com on behalf of Wayne Sumner Sent: Fri 6/13/2008 5:25 PM To: utah-astronomy(a)mailman.xmission.com Subject: Re: [Utah-astronomy] DesctructiveGear.com Seth, If it's still available, I'll buy it for $180, battery included. Please let me know quick. I have a star party coming up soon. Thanks, Wayne A. Sumner Math/Physics/Astronomy/Engineering Boy's Tennis Coach Northridge High School Davis School District (801) 402-8610 >>> "Seth Jarvis" <SJarvis(a)slco.org> 06/13/08 1:22 PM >>> OK, I've completely lost my mind. I just ordered the 100 mW version of the laser. That means my one-day-old-perfect-condition 75 mW (actually specs at 80) is up for sale for the $180 it cost me, but I'll throw in the $10 battery I put in it yesterday. Seth -----Original Message----- From: utah-astronomy-bounces(a)mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Seth Jarvis Sent: Friday, June 13, 2008 1:11 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] DesctructiveGear.com Nope, this will be my first report to the group. My 75mW green laser from DestructiveGear.com arrived yesterday (Thursday), less than a week after I ordered it. Considering it came in an envelope with a Taiwanese postmark, that's pretty impressive. The laser seems to be very well made and came with a bench test report indicating that over its 20 second quality control test it had a mean output of a skosh over 80 mW. This little bugger is _bright_. If you want to do the electrical tape cutting and match lighting, this laser is just _barely_ able to do that. I'd say go for the 100 mW if you're dreaming of a death ray. As a night sky pointer, it's simply incredible. As I told Chuck off-line, a person with a P.A. system and one of these lasers could do a star & constellation ID session for a very large audience. I had my son stand over a hundred feet from my last night in city lighting conditions and the beam still looked like a bright pole of light going right to the star he was pointing at. I wish I'd bought the 100 mW laser, but this little bugger for $180 is still sweet - my favorite new toy. BTW, it uses fairly expensive 123 Lithium camera batteries. The best deal I've found for them is a box of 12 from surefire.com. Delivered they'll run you about $26 for the dozen, compared to about $8-$10 each if bought singly from the local supermarket. It's a blast! Seth Jarvis, Director Clark Planetarium -----Original Message----- From: utah-astronomy-bounces(a)mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Chuck Hards Sent: Friday, June 13, 2008 12:54 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] DesctructiveGear.com I got a tracking update that my 100mw has cleared Customs. Should be here in a few days. Seth has reported terrific incendiary news on his 75mw. (Did you report to the group while I was off-line?) _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com

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Spectral Studies on Ealing - continued attempt
by Canopus56 15 Jun '08

15 Jun '08

>From June 8 imaging session. These are initial steps in the process. I haven't yet reached calibrating the spectra for dispersion or identifying elements. This is an improvement over my initial May 31 session. Making a drift strip spectrograph of Arcturus http://gallery.utahastronomy.com/main.php?g2_itemId=11543 Imaging partial spectrographs through Johnson B, V and R reference filters http://gallery.utahastronomy.com/main.php?g2_itemId=11545 Registering the full spectrograph through Clear filter with the Johnson B, V and R reference filtered images using Vspec http://gallery.utahastronomy.com/main.php?g2_itemId=11547 The partial spectrographs registered to the Clear filter full spectrograph by X-axis pixel http://gallery.utahastronomy.com/main.php?g2_itemId=11549 More to come. Peace - Kurt

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Ealing test image - DSO M13 - 20080613
by Canopus56 15 Jun '08

15 Jun '08

A test image of M13 taken after drive controller calibration with a Meade DSI Pro I. No dark or white flats; no hot pixel fix. - Kurt http://gallery.utahastronomy.com/main.php?g2_itemId=11533

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DesctructiveGear.com
by Chuck Hards 15 Jun '08

15 Jun '08

Has anybody purchased laser products from DestructiveGear.com, either directly or through Google? Ever had customs intercept your merchandise?

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