2010 Astronomy Festival http://www.nps.gov/brca/parknews/2010-astronomy-festival.htm patrick
Hi Friends, It's tardy, but here's my report on the talk Dale gave last week. It's thrilling that people are actually doing this kind of astronomy in Utah. Best wishes, Joe http://www.deseretnews.com/blog/47/Nightly-News-Astronomy-blog.html -
Thanks for the very kind words Joe! Hopefully I was able to convey what I feel is the most important aspect about amateur radio astronomy - and that is the wide variety of things that an amateur can pursue. At the SLAS meeting I was asked about links for some of the things I mentioned such as SARA and Radio Jove, etc. I'll put those together as a comment in the blog. A couple other notes. During the talk I said that Karl Jansky noticed that the signal appeared four minutes *later* each day -- err wrong. I meant to say that he saw it four minutes earlier each day (i.e. the sidereal rate). If anyone caught that and thought, "what a total doofus" - please forgive me. Also, to answer a question that was asked - the low loss cable I use is 50 ohm impedance. Clear skies, Dale.
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah- astronomy-bounces@mailman.xmission.com] On Behalf Of Joe Bauman Sent: Wednesday, June 23, 2010 8:07 PM To: Utah Astronomy Subject: [Utah-astronomy] Dale Hooper's fascinating talk
Hi Friends, It's tardy, but here's my report on the talk Dale gave last week. It's thrilling that people are actually doing this kind of astronomy in Utah. Best wishes, Joe
http://www.deseretnews.com/blog/47/Nightly-News-Astronomy-blog.html
-
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
Thank you, Dale. I'm so impressed with the energy and interesting approach to nature that amateur astronomers display. My feeling is it has something to do with an intelligent person's urge to personally find out something about the fundamentals. Best wishes, Joe --- On Thu, 6/24/10, Dale Hooper <Dale.Hooper@sdl.usu.edu> wrote: From: Dale Hooper <Dale.Hooper@sdl.usu.edu> Subject: Re: [Utah-astronomy] Dale Hooper's fascinating talk To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Thursday, June 24, 2010, 10:07 AM Thanks for the very kind words Joe! Hopefully I was able to convey what I feel is the most important aspect about amateur radio astronomy - and that is the wide variety of things that an amateur can pursue. At the SLAS meeting I was asked about links for some of the things I mentioned such as SARA and Radio Jove, etc. I'll put those together as a comment in the blog. A couple other notes. During the talk I said that Karl Jansky noticed that the signal appeared four minutes *later* each day -- err wrong. I meant to say that he saw it four minutes earlier each day (i.e. the sidereal rate). If anyone caught that and thought, "what a total doofus" - please forgive me. Also, to answer a question that was asked - the low loss cable I use is 50 ohm impedance. Clear skies, Dale.
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah- astronomy-bounces@mailman.xmission.com] On Behalf Of Joe Bauman Sent: Wednesday, June 23, 2010 8:07 PM To: Utah Astronomy Subject: [Utah-astronomy] Dale Hooper's fascinating talk
Hi Friends, It's tardy, but here's my report on the talk Dale gave last week. It's thrilling that people are actually doing this kind of astronomy in Utah. Best wishes, Joe
http://www.deseretnews.com/blog/47/Nightly-News-Astronomy-blog.html
-
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
Hey Dale you have any need for coax w/ BNC female at both ends?? we're taking down a lab and there are many cables w/ BNC fittings, sorry I don't know the impedance at the moment. Some cables are 6ft, some are 50ft Aloha Rob
Hi Rob, I appreciate the offer. I am going to be purchasing a 100 ft cable later in the year when I get ready to try my hand at some interferometry. But, unfortunately, I suspect that I won't be able to use the cables that you have. Regular coax is very lossy at 1.4 GHz. Thanks again & clear skies, Dale.
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah- astronomy-bounces@mailman.xmission.com] On Behalf Of Rob Ratkowski Photography Sent: Thursday, June 24, 2010 10:27 AM To: Utah Astronomy Subject: Re: [Utah-astronomy] Dale Hooper's fascinating talk
Hey Dale
you have any need for coax w/ BNC female at both ends?? we're taking down a lab and there are many cables w/ BNC fittings, sorry I don't know the impedance at the moment. Some cables are 6ft, some are 50ft
Aloha Rob
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
Hi Dale I will gather all the cables at the site I suspect they could go between preamp and receiver or some other gear. I'm always amazed when good items are disposed of because they are not needed but quite useful. If you needem', I gottem' Aloha Rob
OK, It's time for me to get down to doing something I've never succeeded at before, taking flats. Could any of you experienced astrophotographers fill me in on some essentials? First, I assume you have to take a series of 'em for each image you get; in fact, flats for luminosity and flats for r, g and b. Is that so? How many do you take? Second, how can you take them when it's dark outside and you want to slew to another target? Please give me a few hints. Many thanks, Joe
On 25 Jun 2010, at 21:20, Joe Bauman wrote:
OK, It's time for me to get down to doing something I've never succeeded at before, taking flats. Could any of you experienced astrophotographers fill me in on some essentials? First, I assume you have to take a series of 'em for each image you get; in fact, flats for luminosity and flats for r, g and b. Is that so? How many do you take? Second, how can you take them when it's dark outside and you want to slew to another target? Please give me a few hints. Many thanks, Joe
Short question requiring a pretty long answer. Making flats takes a lot less time than darks. Darks have to be the same chip temperature and exposure length as the light images whereas flats also need to be at the same temperature but only need to be long enough exposure to reach about half the saturation point of your camera. As an example my camera saturates at 50,000 or 65,000 depending on what binning I'm using. So I try to shoot flats that are about 25,000 to 30,000. With the light source I use that's usually about 2 to 4 seconds. Flats (and darks) must be shot with the chip at the same temperature and the same binning as the lights. You need a separate flat for each filter you use to make the lights. So if you're shooting R, G, B and luminance you need a flat for each of those. Shoot several flats through each filter (I do 15 each though I've heard of others who shoot more). Then median combine each set into a master flat. That way you end up with master R, G, B and luminance flats. Although it takes a lot longer to make master darks they can be reused for quite some time assuming they were made at the same exposure, temperature and binning as the lights. Flats can be reused too but ONLY if the scope is not refocused and the camera is not moved (rotated) or removed. If focus is changed significantly or if the camera is moved or removed you have to make all new flats. That's the reason I leave the camera securely bolted to the scope all the time. I've left what can be the most problematic part of making flats for last and that's the physical set up of the equipment. In my case with a fixed observatory it's pretty straight forward. I wait until it's dark, hang a piece of white cardboard half a meter or so in front of the scope, illuminated the cardboard from the other side of the room with a diffuse light source and fire way. How in the world that is done with a portable setup is beyond me. I know Cindy and Jerry Foote came up with a rather interesting device made of baby diapers (to diffuse dawn/dusk sky light) that fits over the front of their scopes. I've also heard of light boxes that fit over the front of the scope. Maybe those here that have done portable astroimaging can chime in on how they do it. So, let's see how many of what you need to shoot. Let's say you're going to be shooting some spectacular Tyleresque image with the chip cooled to -10, the binning set to 2x2 and a series of 5 minute exposures using red, green, blue and clear filters. To make the master dark: 15 - 5 minute exposure darks, -10 degrees, binned 2x2. All 15 darks are then median combined into a master dark. To make the master flats: 15 - X" (X equals whatever exposure is need to expose the chip half way to saturation) exposure flats, -10, 2x2, shot through the clear filter. All 15 are then median combined into a master clear flat. 15 - X" exposure flats, -10, 2x2, shot through the red filter. All 15 are then median combined into a master red flat. 15 - X" exposure flats, -10, 2x2, shot through the green filter. All 15 are then median combined into a master green flat. 15 - X" exposure flats, -10, 2x2, shot through the blue filter. All 15 are then median combined into a master blue flat. I guess it looks a bit complicated and time consuming (I know it did to me when I first started thinking about doing color imaging). Maybe that's why so few people does serious astroimaging. But fortunately Jerry Foote was there to guide me along (thanks again Jerry). It always helps to have a mentor. As with so many things once you've got a system down it's really not that complicated. As for time consuming, the flats are not that bad since they are so short. But, yeah, the darks do take a lot of time if your light frames are any longer than a minute or two. Happily, since the camera does not even have to be on the scope to make darks you could just put the camera in a dark room some cloudy night, cool it down, set the binning and instruct the software to take 15 darks and go have dinner. I hope this helps. If you've got more questions let me know. Or maybe we could talk it over at an upcoming SLAS function. And now (appropriately enough) I'm going to turn all the darks and flats I shot last night into masters. Boringly yours, patrick
Thanks very much, Patrick, this is great. I plan to build a portable light box that I can put over the end of my scope. Here's another dumb newby-type question: what do you mean by 50,000, etc.? Best wishes, Joe --- On Sat, 6/26/10, Patrick Wiggins <paw@wirelessbeehive.com> wrote: From: Patrick Wiggins <paw@wirelessbeehive.com> Subject: Re: [Utah-astronomy] Newby-type question To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Saturday, June 26, 2010, 12:10 AM On 25 Jun 2010, at 21:20, Joe Bauman wrote:
OK, It's time for me to get down to doing something I've never succeeded at before, taking flats. Could any of you experienced astrophotographers fill me in on some essentials? First, I assume you have to take a series of 'em for each image you get; in fact, flats for luminosity and flats for r, g and b. Is that so? How many do you take? Second, how can you take them when it's dark outside and you want to slew to another target? Please give me a few hints. Many thanks, Joe
Short question requiring a pretty long answer. Making flats takes a lot less time than darks. Darks have to be the same chip temperature and exposure length as the light images whereas flats also need to be at the same temperature but only need to be long enough exposure to reach about half the saturation point of your camera. As an example my camera saturates at 50,000 or 65,000 depending on what binning I'm using. So I try to shoot flats that are about 25,000 to 30,000. With the light source I use that's usually about 2 to 4 seconds. Flats (and darks) must be shot with the chip at the same temperature and the same binning as the lights. You need a separate flat for each filter you use to make the lights. So if you're shooting R, G, B and luminance you need a flat for each of those. Shoot several flats through each filter (I do 15 each though I've heard of others who shoot more). Then median combine each set into a master flat. That way you end up with master R, G, B and luminance flats. Although it takes a lot longer to make master darks they can be reused for quite some time assuming they were made at the same exposure, temperature and binning as the lights. Flats can be reused too but ONLY if the scope is not refocused and the camera is not moved (rotated) or removed. If focus is changed significantly or if the camera is moved or removed you have to make all new flats. That's the reason I leave the camera securely bolted to the scope all the time. I've left what can be the most problematic part of making flats for last and that's the physical set up of the equipment. In my case with a fixed observatory it's pretty straight forward. I wait until it's dark, hang a piece of white cardboard half a meter or so in front of the scope, illuminated the cardboard from the other side of the room with a diffuse light source and fire way. How in the world that is done with a portable setup is beyond me. I know Cindy and Jerry Foote came up with a rather interesting device made of baby diapers (to diffuse dawn/dusk sky light) that fits over the front of their scopes. I've also heard of light boxes that fit over the front of the scope. Maybe those here that have done portable astroimaging can chime in on how they do it. So, let's see how many of what you need to shoot. Let's say you're going to be shooting some spectacular Tyleresque image with the chip cooled to -10, the binning set to 2x2 and a series of 5 minute exposures using red, green, blue and clear filters. To make the master dark: 15 - 5 minute exposure darks, -10 degrees, binned 2x2. All 15 darks are then median combined into a master dark. To make the master flats: 15 - X" (X equals whatever exposure is need to expose the chip half way to saturation) exposure flats, -10, 2x2, shot through the clear filter. All 15 are then median combined into a master clear flat. 15 - X" exposure flats, -10, 2x2, shot through the red filter. All 15 are then median combined into a master red flat. 15 - X" exposure flats, -10, 2x2, shot through the green filter. All 15 are then median combined into a master green flat. 15 - X" exposure flats, -10, 2x2, shot through the blue filter. All 15 are then median combined into a master blue flat. I guess it looks a bit complicated and time consuming (I know it did to me when I first started thinking about doing color imaging). Maybe that's why so few people does serious astroimaging. But fortunately Jerry Foote was there to guide me along (thanks again Jerry). It always helps to have a mentor. As with so many things once you've got a system down it's really not that complicated. As for time consuming, the flats are not that bad since they are so short. But, yeah, the darks do take a lot of time if your light frames are any longer than a minute or two. Happily, since the camera does not even have to be on the scope to make darks you could just put the camera in a dark room some cloudy night, cool it down, set the binning and instruct the software to take 15 darks and go have dinner. I hope this helps. If you've got more questions let me know. Or maybe we could talk it over at an upcoming SLAS function. And now (appropriately enough) I'm going to turn all the darks and flats I shot last night into masters. Boringly yours, patrick _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
Evening Joe, On 26 Jun 2010, at 00:30, Joe Bauman wrote:
Thanks very much, Patrick, this is great. I plan to build a portable light box that I can put over the end of my scope. Here's another dumb newby-type question: what do you mean by 50,000, etc.? Best wishes, Joe
I don't know what the units of measure are but think of it this way: When there are no photons hitting a pixel the number would be 0 (zero). The more photons hitting the pixel the higher the number until that pixel is holding as many photons as it can. When it gets to that point (holding as many pixels as it can) the pixel is said to be saturated. Another analogy I've heard is comparing each pixel to a bucket. Like a bucket a pixel can only hold so much until it starts to overflow. Each chip has a published saturation point which (I'm guessing) should be listed in the manual. What imager are you using? Clear skies (which they actually are here near SPOC just now), patrick p.s. ~90 minutes until the start of umbral phase of the eclipse.
Hi Patrick, I use an SBIG ST-402ME. I don't know where to find those numbers. Are they part of the info that is recorded with the image? Thanks again, Joe --- On Sat, 6/26/10, Patrick Wiggins <paw@wirelessbeehive.com> wrote: From: Patrick Wiggins <paw@wirelessbeehive.com> Subject: Re: [Utah-astronomy] Newby-type question To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Saturday, June 26, 2010, 2:50 AM Evening Joe, On 26 Jun 2010, at 00:30, Joe Bauman wrote:
Thanks very much, Patrick, this is great. I plan to build a portable light box that I can put over the end of my scope. Here's another dumb newby-type question: what do you mean by 50,000, etc.? Best wishes, Joe
I don't know what the units of measure are but think of it this way: When there are no photons hitting a pixel the number would be 0 (zero). The more photons hitting the pixel the higher the number until that pixel is holding as many photons as it can. When it gets to that point (holding as many pixels as it can) the pixel is said to be saturated. Another analogy I've heard is comparing each pixel to a bucket. Like a bucket a pixel can only hold so much until it starts to overflow. Each chip has a published saturation point which (I'm guessing) should be listed in the manual. What imager are you using? Clear skies (which they actually are here near SPOC just now), patrick p.s. ~90 minutes until the start of umbral phase of the eclipse. _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
Hi Joe, On 26 Jun 2010, at 11:23, Joe Bauman wrote:
Hi Patrick, I use an SBIG ST-402ME. I don't know where to find those numbers. Are they part of the info that is recorded with the image? Thanks again, Joe
Looking through the owners manual for the 402 I see: Non-ABG CCDs 100,000 electrons ABG CCDs 50,000 electrons But, just to throw a fly in the ointment, while looking elsewhere on the SBIG site I found this statement: "Since the same flat field is added to itself a number of times, be sure that you do not saturate the flat field image by starting with pixel values too high. Typically try to keep the pixel values between 10% to 20% of saturation for this purpose. For single flat field images, try to keep the values to approximately 50% of saturation." If I'm reading that right it would seem to indicate that one goes for 50% of saturation only if doing a single flat field. For multiple flat fields (which I'm pretty sure most everyone recommends) to be combined into a master flat that should only be 10 to 20 percent. So at this point I think I'll bow out and wait for more knowledgeable folks like Jerry and Tyler to chime in and set me straight. Sorry for the confusion, patrick
Thanks, Patrick. I'll get it yet! Best wishes, Joe --- On Sat, 6/26/10, Patrick Wiggins <paw@wirelessbeehive.com> wrote: From: Patrick Wiggins <paw@wirelessbeehive.com> Subject: Re: [Utah-astronomy] Newby-type question To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Saturday, June 26, 2010, 3:21 PM Hi Joe, On 26 Jun 2010, at 11:23, Joe Bauman wrote:
Hi Patrick, I use an SBIG ST-402ME. I don't know where to find those numbers. Are they part of the info that is recorded with the image? Thanks again, Joe
Looking through the owners manual for the 402 I see: Non-ABG CCDs 100,000 electrons ABG CCDs 50,000 electrons But, just to throw a fly in the ointment, while looking elsewhere on the SBIG site I found this statement: "Since the same flat field is added to itself a number of times, be sure that you do not saturate the flat field image by starting with pixel values too high. Typically try to keep the pixel values between 10% to 20% of saturation for this purpose. For single flat field images, try to keep the values to approximately 50% of saturation." If I'm reading that right it would seem to indicate that one goes for 50% of saturation only if doing a single flat field. For multiple flat fields (which I'm pretty sure most everyone recommends) to be combined into a master flat that should only be 10 to 20 percent. So at this point I think I'll bow out and wait for more knowledgeable folks like Jerry and Tyler to chime in and set me straight. Sorry for the confusion, patrick _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
participants (4)
-
Dale Hooper -
Joe Bauman -
Patrick Wiggins -
Rob Ratkowski Photography