Re: [Utah-astronomy] Wow!!! (SLAS Maui imaging session)
Rather than do a gazillion individual email replies, here are some short responses to each: ---------------
Patrick 2010-01-21 19:15 -700 Your comment about the tracking errors prompted me to look through images others have made using the 2-meter. Many have shorter exposures but some were longer. But all had round stars. Good to know its an anomaly for our SLAS imaging session. Having to the "star-be-gone" thing to recover the images is pretty tediuous.
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Tyler Allred 2010-01-21 21:27 -700 I am curious about the cleaning process you are using. . . . In particular, I notice that the bright star at the top of the blue image is not seen in the green and red images. Also, the pulsar has been removed in some of the images, although the shockwaves are clearly seen. . . . How are you doing the cleaning... a filter?? No auto-filter - it was a 2 hour hand-job. I went through each image and where the stars were not round, I used a GIMP-Heal or GIMP-Clone tool to erase them. For the three largest stars, sometimes that heal operation left a visually obvious artifact and the GIMP-Smudge tool had to be used to smudge the fix area.
I was not consistent about removing the same stars in each layer. The main point is that any larger round-stars are removed so the oval shape of any star (regardless of its size) is hidden when the final foregound transparent alpha layer just containing round stars is added back in. ---------------
Daniel Holmes 2010-01-21 19:39 -700 The only complaint that I would have about that night is there wasn't any explanation as to why we were doing the settings we were doing . . . My recollection is that we were still learning to use the telescope camera, since it was the club's first open session with the Faulkes. 300 seconds is a good ball park figure to get a feel what the exposure response curve of the camera was. 300 secs is a good starting point estimate.
As Tyler noted during the 1-15-2010 session, one of the drawbacks of Faukles setup is that you cannot get immediate access to the processed FITS images. With a normal small scope setup you would take a 100 to 300 sec exposure, open the FITS file and check the exposure levels in a histogram of the image. If we had had that capability, we would have immediately been able from the first image to determine that the capture a-d-us (pixel values) were way too low and could have doubled the exposure times. As it is, what the group collectively did was the right choice at the time but in retrospect did not work out. I hope some of that can be fixed with some post-imaging processing. For me, this is a consistent problem that I've seen using commercial roboscopes at GRASS - no consistent online calculator or table of recommended starting exposures for each scope-camera-filter combination, so you are not burning up rationed or expensive online scope time. -------------- I also have one other general question for attendees at the session: Q1. What was the magnification used to make the images? I believe I heard it the images had an 8 x 8 arcmin TFOV. Would that be about 390 power? ( 52 degs / (8 degs / 60 degs) ) Clear Skies, Kurt
Hi, all -- I was browsing KSL's classifieds, and saw that someone in Duchense was selling the following setup: - Celestron 4-inch refractor (c4-r or c102hd, dep. on age) on somewhat shabby EQ mount. - a scope "highly recommended" by Ed Ting at scopereviews.com at a price of $750. - 2.3 mm Celestron xcel EP - a decent, if inexpensive EP - 5x Powermate (serious stuff, a couple hundred or more new) - a "filter". The photo of the filter makes me think it is some sort of UHC or LP filter -- it's kind of shiny for $300. Now the downside would be that the supplied mount is probably inferior, but the accessories themselves are almost worth the price of admission. Anyway, I don't want to be a "multiple-scope" guy. My 6" f/5 reflector is probably pound-for-pound and photon-for-photon pretty close to a 4" refractor (although I admit being tempted). I saw it and thought that if someone has the gas money, or needs to head east anyway, it seems like a great deal, especially if the seller could say more about what the filter was (if it's a UHC, it's probably about $100 new). On the topic of filters, the always-sketchy "telescopes.com" offers a set of Zhumell filters for about $100 with free shipping, including a variable polarizing filter, a UHC (narrowband) filter, a broadband filter, and an O-III filter (1.25" format). I couldn't resist. I wanted to offer a decent review, but with inversion, and the pathetic weather lately, I can't be too precise. What I can say is this: From my backyard (three blocks from Redwood Rd), I cannot normally detect the dumbbell, but other DSO (the ring, M81/82, M31, Messier open clusters, globulars in Sagit./Ophiuc. region) are pretty easy. I can definitely see it (M27) by passing the O-III or UHC filters in front of the EP when looking (after which, I can see it w/o a filter). M42 grows with any of the filters (except, obviously, the polarizing one) in. So, with the Orion or Lumicon UHC filters at $100 each, I think the Zhumell set is not too bad. Probably not great, but I can find planetaries at home, without having to travel, for a pretty low cost. I'll let you know if the broadband helps with galaxies, if there is ever a clear-ish night with not a lot of moon.... ---- Rev. Michael A. van Opstall Department of Mathematics, University of Utah Office: JWB 313 opstall@math.utah.edu
As the subject implies this might be more of interest to Tyler and Kurt but I thought I'd post here in case anyone else would be interested. As it turns out the Faulkes raw files are available but only on request. I just rang JD about this and he is going to download all of the raw stuff (lights, darks, flats, bias) from our recent M1 session, zip them up and post them to he web. He'll let us know the URL when he gets that done. I asked about a possible option of getting the raw stuff immediately (as they are made). He said that is a frequent request but that the powers that be will not allow it. patrick
Boy, JD is quick! He's got them online already Here's where to find the raw M1 data (all 100+ MB of it): ftp://ftp.ifa.hawaii.edu/INOUT/INCOMING/Armstrong/unprocessed.zip I was not able to download the file using a web browser (I tried Safari, Netscape and IE) but using an FTP client (I use Fetch) the download went well. I was glad to see that only a few of the images show the tracking problems that have been mentioned here. So hopefully one of our imaging meisters will be able to put together a finished product without using the bad ones. patrick On 22 Jan 2010, at 20:23, Patrick Wiggins wrote:
As the subject implies this might be more of interest to Tyler and Kurt but I thought I'd post here in case anyone else would be interested.
As it turns out the Faulkes raw files are available but only on request.
I just rang JD about this and he is going to download all of the raw stuff (lights, darks, flats, bias) from our recent M1 session, zip them up and post them to he web. He'll let us know the URL when he gets that done.
I asked about a possible option of getting the raw stuff immediately (as they are made). He said that is a frequent request but that the powers that be will not allow it.
patrick
The filename is actually unprocessed.zip.zip, which is why it's not working in the link you provided. Try this, it works fine: ftp://ftp.ifa.hawaii.edu/INOUT/INCOMING/Armstrong/unprocessed.zip.zip Dan On Jan 22, 2010, at 8:49 PM, Patrick Wiggins wrote:
Boy, JD is quick! He's got them online already
Here's where to find the raw M1 data (all 100+ MB of it):
ftp://ftp.ifa.hawaii.edu/INOUT/INCOMING/Armstrong/unprocessed.zip
I was not able to download the file using a web browser (I tried Safari, Netscape and IE) but using an FTP client (I use Fetch) the download went well.
I was glad to see that only a few of the images show the tracking problems that have been mentioned here. So hopefully one of our imaging meisters will be able to put together a finished product without using the bad ones.
patrick
On 22 Jan 2010, at 20:23, Patrick Wiggins wrote:
As the subject implies this might be more of interest to Tyler and Kurt but I thought I'd post here in case anyone else would be interested.
As it turns out the Faulkes raw files are available but only on request.
I just rang JD about this and he is going to download all of the raw stuff (lights, darks, flats, bias) from our recent M1 session, zip them up and post them to he web. He'll let us know the URL when he gets that done.
I asked about a possible option of getting the raw stuff immediately (as they are made). He said that is a frequent request but that the powers that be will not allow it.
patrick
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participants (4)
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Canopus56 -
Daniel Holmes -
Michael Vanopstall -
Patrick Wiggins