December 2009 - Utah-Astronomy - mailman.xmission.com

Re: [Utah-astronomy] NGC7320
by Canopus56 24 Dec '09

24 Dec '09

Jerry, My bad. The most recent 300 sec Gras master dark is now available in the project directory for downloading at: http://fisherka.csolutionshosting.net/astronote/photos/processing/ as file "091206_0141_Darks_300_033.zip" 11mb. For reasons that I do not understand, although these master darks are in the GRAS14 calibration file directory, the flat in the dark file is prefixed "G12". i applied it to the luminance image and it did noticeably improve the result. Enjoy, Merry Christmas - Kurt

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NGC7320
by Jerry Foote 24 Dec '09

24 Dec '09

Hi Kurt, Thanks for the links to the raw image as well as the calibration images. I downloaded the calibration zip file and then unzipped the contents. The file that was to contain the Darks was empty so I couldn't work with it. The zipping process might have missed the darks. The Flat image looks reasonable and contains some dust shadows as would be expected. The Bias image is very strange as it has a pronounced gradient from top to bottom. Bias images are supposed to be made with zero integration time (which the FITS header says it is) and simply reflect the read noise in the output amplifier as well as a preset pedestal that prevents negative ADU values. Under normal conditions there is a slight gradient from top to bottom as thermal electrons are formed but usually this is very small and is minimized if the temperature is low. In this image the gradient goes from about 800 to over 1600 ADU's. You might want to check with the GRAS people about this image. It isn't very important as for most processing the bias frame isn't used anyway as the bias information would be normally contained in the Dark frame and gets subtracted out when the Dark is subtracted. The only time bias frames are important is when the Darks are scaled for exposure time or temperature difference, which I assume isn't done here. Kurt this is fun. Thank you for supplying the images and letting us work with the images you have paid for. Jerry Foote ScopeCraft, Inc. 4175 E. Red Cliffs Dr. Kanab, UT 84741 435-899-1255 jfoote(a)scopecraft.com

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Re: [Utah-astronomy] Hawaiian imaging session this evening?
by Canopus56 23 Dec '09

23 Dec '09

Patrick. Thank you for the invite. I was doing last-minute Christmas stuff yesterday afternoon and was not monitoring the listserv, so I missed your invitation. Hope you all had a good time and I am looking forward to hearing about the experience. - Kurt

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Re: [Utah-astronomy] NGC7320
by Canopus56 23 Dec '09

23 Dec '09

P.S. - The project directory for downloading is: http://fisherka.csolutionshosting.net/astronote/photos/processing/ The applicable two zip files are: "G14 Calib.zip" 27Mb a collection of zip folders contains flats "G14-kfisher-NGC7320-W-250-C-10-X1-Luminance-001-UT023114.fit.zip" 13Mb the raw luminance image as received from GRASS - Kurt P.S. - One thing that GRAS does not have is a table of the image processing settings for their preplanned image capture filters. Such a table would help in terms of planning exposures by pre-tweaking their baseline settings "galaxies" "bright nebula" "dim nebula" etc.

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NGC7320
by Canopus56 23 Dec '09

23 Dec '09

Jerry - The short answer to your prior question "In your experience is it difficult to get time on a particular scope or do you post a request which gets put into the ACP planner queue?" is "Yes, it is difficult to get time on the research grade scopes because they are qued up with ACP imaging plans." I suspect that this is weather related and am keeping an eye on the system to see if, during a string of clear weather dates, the ACP ques complete and the research grade scopes then open up. I have uploaded the raw luminance image generated by the Gras 14 scope and the separate calibration files. GRAS did not take real time calibration times. There is a directory that contains calibration files stored by exposure seconds. These master flats are updated every few months. I grabbed what I felt was appropriate. If you feel other calibration files are needed, let me know and I'll hunt them. > I looked at the FITS header and it indicated that the exposure was > 250 seconds. I erred in my report. The exposure was 250 seconds. I believe this was auto-selected by GRAS. I used their default "dim galaxy" filter setting. > Did you take multiple darks at the same exposure and temperature? > Also did you take multiple flats? See comments above regarding GRAS flats. I will have to log on and determine if this is configurable and if you can order real time darks and flats. > Were you charged for the time to take these? Not for taking the flats. See discussion above regarding pre-calibrated flats. FTP download time is a no charge activity. GRAS has a variable pricing plan that depends on the scope. It is based on a flat fee plus points per hour. See the table "Hourly Rate in Points Per Hour" midway down these pages noting the equivalent hours of usage: http://grasbill.global-rent-a-scope.com/pricelist/pricelist.asp?Plan=Plan-40 http://grasbill.global-rent-a-scope.com/pricelist/pricelist.asp?Plan=Plan-90 As a practical matter, a high-resolution image on any of the research grade scopes takes about 6 ot 10 minutes to execute. As a practical matter, you can squeeze out maybe four or five images on the research grade scopes before you have to add another 50 points for $50 when using the basic $40 dollar per month plan. It works out to around $5 to $10 per image. As I mentioned at that outset, this is expensive to use. It is something I am only test driving for a couple of months during the winter on a part of the world I probably will never travel to. (The Northern Hemisphere NGC7320 image was taken on a lark when Australia was clouded out.) Let me know if you need any more info. My apologies for the high response times. Work and Christmas and the rest of my life - you know the drill. - Kurt

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Re: [Utah-astronomy] NGC7320
by Canopus56 23 Dec '09

23 Dec '09

Jerry - > The noise is about what I would expect with this camera running at -10 deg > and a 240 second exposure. . . . . Would it be possible for you to post on > your site the raw image as well as the darks and flats you used? Jerry, it was a 300 sec exposure. I 'll get the raw, dark and flats up on a public server in the next couple of days so anyone can grab them. The files are 13megs each so initially I did not want to post the source files figuring no one would download that much data. > I have been following your adventures with the > Rent-a-scope program. In your experience is it difficult to get time > on a particular scope or do you post a request which gets > put into the ACP planner queue? To keep the cost within - for me - reason, I subscribed to the $40 per month GRAS plan which does not include scripting. The next subscription level is at $90 p/m and includes scripting. I have never felt scope resource constrained with GRAS Australia. During the best time to use it from Utah - 4am to 8am MST - there is always one high-end refractor free (106 Tak) and one large 10 inch or greater astrograph with a high-end ST camera available. One usually is available on login or becomes available at most with a 5 to 10 minute wait. Since my experience level isn't such that I am hot for just one specific larger aperature scope. Therefore, I have not felt constrained. For GRAS New Mexico, the situation is the same but the probability of having to wait a few minutes before a scope opens up is higher. For both the New Mexico and Australia scopes - at least for this time of year - weather outages is the constraining factor. Even in southern hemisphere Australia, I am average maybe a 25% chance of having the domes open. The other 60% of the time they are weather closed. Another 15% is service outages. Because of that, I'm not too optimistic that you would get that much out of imaging by a scripted run. It felt is was better to have a list of targets of opportunity and to get what you can manually when the weather is clear. The GRAS high-end mounts and auto-exposure all run spot on target as instructed. IMHO, auto-focus is less than what one could get with monitored manual or monitored auto-focus. I haven't used it, but I'd feel confident about submiting scripts and just picking up the image results by FTP later. My next planned test targets are Mars in northern hemisphere and a comet in the southern hemisphere. Overall, the experience is much less satisfying than setting up my own scope and taking images with my inexpensive equipment. I view it mostly as a way to capture a few images to play around with during the overcast northern Utah winter season. It's also educational to work with these high-end megapixel cameras and mounts that I ordinarily am unable to afford. One quickly gets the message that the name of the imaging game is "tracking accuracy, tracking accuracy and tracking accuracy" followed by "long-term exposure, long-term exposure and long-term exposure." Those are just my general impressions. Hope that helps. Clear Skies - Kurt

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NGC7320
by Jerry Foote 22 Dec '09

22 Dec '09

Hi Kurt, I downloaded the image "20091220 NGC7320FlattedClip.fit" and opened it. You mentioned that it had been "dark and white flatted". In looking at the image it appears to have considerable thermal noise. The noise is about what I would expect with this camera running at -10 deg and a 240 second exposure. In looking at the FITS header, in shows that you had done some processing on the raw image. I wonder if the link you posted is not the dark subtracted image? Would it be possible for you to post on your site the raw image as well as the darks and flats you used? I have been following your adventures with the Rent-a-scope program. In your experience is it difficult to get time on a particular scope or do you post a request which gets put into the ACP planner queue? Jerry Foote ScopeCraft, Inc. 4175 E. Red Cliffs Dr. Kanab, UT 84741 435-899-1255 jfoote(a)scopecraft.com

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M101
by David Rankin 22 Dec '09

22 Dec '09

Got this the same night as the Rosette :) http://www.slas.us/gallery2/main.php?g2_itemId=2743&g2_imageViewsIndex=1 Done for a few days, have to go work. Hopefully be able to get some imaging done Tuesday night weather permitting. Cheers, David

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NGC2070 Tarantula Neb 12-18-2009 via GRAS roboscope
by Canopus56 22 Dec '09

22 Dec '09

http://www.slas.us/gallery2/main.php?g2_itemId=2739 Taken from SLC this morning using a 12" GRAS roboscope stationed in Victoria, Australia. - Kurt

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Any suggestions?
by Patrick Wiggins 21 Dec '09

21 Dec '09

Hi all, The SLAS member information file is in the process of being updated for the new year. I've already emailed SLAS members asking for input. But it occurred to me that it might be helpful to get input from non-SLASers who might look at the document with "fresh eyes". Especially those with an interest in astronomy (everyone here) who might have questions about SLAS that are not answered by the 2009 version of the document which is available to all on the SLAS website. So please have a look at the draft of the 2010 version and let me know about anything you think should be added, removed, reworded and so on. I'd even like to hear about simple misspellings: http://users.wirelessbeehive.com/~paw/slas/NEWMEM2010DRAFT.PDF Many thanks, patrick Lame Duck SLAS Sec/Treas (only 11 days left until Joe "gets" to take over <g>)

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