Thank you for your nice large-field picture of Sirius. I have blown it up to approximate my much smaller field pictures. Your photo has been quite helpful in my study of the starfield around Sirius. I have been able to match most of the stars to my own images. I have been working with my new Celestron system. I have attached a pic of the field southwest of Sirius which displays one of the stars also seen in your photo. It's about 10th magnitude and I estimate separation of about 193 arcseconds and position angle of about 200 degrees from Sirius on March 25th. I can't seem to get this object to match up. I wonder if you tell me what was the date of your photo? I suspect I'm just making an error, but I also wonder whether there might have been some movement of the object (?). I have rotated my picture to orient North upward and West is to the right.
This is a stack of about 2500 frames. I'm starting to get an appreciation for the type of exposure I may need in order not to wash out the area where the pup might be seen.
Thanks, again,
Thad
Quote:
Originally Posted by Vince G
G'day Thad,
Sorry for my delay.
I uploaded a full image of Sirius taken with a 6 megapixel QHY8 camera.
The field of view is about 170x111 arc mins. A 1 sec exposure.
I hope you can adjust your seeing of this image, it's only a 50% jpeg.
North is up and east is to the left in this image.
If you point your scope south to a star then drive or push the tube down, you will then see the stars move to the northside of your eyepiece.
Again, if you drive or push the tube west, you will see the stars move to the east side of your eyepiece. More mirrors, more changes
You may be able to image the pup with your equipment if you can increase the magnification and stack a lot of the images. There are a few good programs freely availabe for that purpose.
G'day Thad,
I'm sorry, but I cannot enlarge your image, and can't see any stars except Sirius.
It was 4th March at UT 09:36 when my image was taken.
See if you can post another image.
Vince
Quote:
Originally Posted by Thad C.
Hello Vince
Thank you for your nice large-field picture of Sirius. I have blown it up to approximate my much smaller field pictures. Your photo has been quite helpful in my study of the starfield around Sirius. I have been able to match most of the stars to my own images. I have been working with my new Celestron system. I have attached a pic of the field southwest of Sirius which displays one of the stars also seen in your photo. It's about 10th magnitude and I estimate separation of about 193 arcseconds and position angle of about 200 degrees from Sirius on March 25th. I can't seem to get this object to match up. I wonder if you tell me what was the date of your photo? I suspect I'm just making an error, but I also wonder whether there might have been some movement of the object (?). I have rotated my picture to orient North upward and West is to the right.
This is a stack of about 2500 frames. I'm starting to get an appreciation for the type of exposure I may need in order not to wash out the area where the pup might be seen.
Thanks for the timing of your photo. That will help tremendously in my attempt to identify the object in question.
Sorry for the low quality picture. I'm attaching the jpeg as it was produced from Registax, but adjusted in contrast, brightness (to bring out my star in question) and rotated to bring North up and West to the right (taken March 26th, 0214 UT, Celestron C11 with f6.8 focal reducer, Logitech Quickcam 4000, 1/15th sec frames, 2496 frames out of about a 3 min. avi file). The field is approximately 4x6 arc minutes (distance between the unknown object and Sirius is 193 arc seconds (calibrated using 208 arcsecond separation of Epsilon Lyrae) , at a 204 degrees position angle (West identified by separate exposure as drive is turn off).
I'm also attaching some color inverted and annotated pictures (but croppped and compressed). One was taken with my old 6" Newtonian reflector in January and the other is a cropped, color inverted and compressed version of the above March 26th image.
You clearly imaged the object I'm trying to identify on March 4th. Any idea what it is, or how to identify it? I haven't had any luck with online sky surveys or catalogs.
G'day Thad,
I haven't been able to identify it yet either. I use TheSky6 Pro, but it isn't shown, even with the UCAC catalogue.
I'll try and get a better image tonight and do astrometry on it.
You're taking good shots with your gear.
If you want a free sky chart program, have a look at Cartes Du Ciel at
>www.stargazing.net/astropc/< it is supposed to be pretty good. If you get some catalogs you may find what your looking for.
Regards
Vince
Quote:
Originally Posted by Thad C.
Hey Vince,
Thanks for the timing of your photo. That will help tremendously in my attempt to identify the object in question.
Sorry for the low quality picture. I'm attaching the jpeg as it was produced from Registax, but adjusted in contrast, brightness (to bring out my star in question) and rotated to bring North up and West to the right (taken March 26th, 0214 UT, Celestron C11 with f6.8 focal reducer, Logitech Quickcam 4000, 1/15th sec frames, 2496 frames out of about a 3 min. avi file). The field is approximately 4x6 arc minutes (distance between the unknown object and Sirius is 193 arc seconds (calibrated using 208 arcsecond separation of Epsilon Lyrae) , at a 204 degrees position angle (West identified by separate exposure as drive is turn off).
I'm also attaching some color inverted and annotated pictures (but croppped and compressed). One was taken with my old 6" Newtonian reflector in January and the other is a cropped, color inverted and compressed version of the above March 26th image.
You clearly imaged the object I'm trying to identify on March 4th. Any idea what it is, or how to identify it? I haven't had any luck with online sky surveys or catalogs.
By the way, I may not have rotated the right-most image properly, so North may be off a few degrees. The wider field view, though, can be matched with 3 known stars to the SW of Sirius to derive coordinates exactly.
Thanks for the advice re Carte du Ciel. I'll give it a whirl. I have been using Stellarium (which is not so detailed on the small field we've been discussing).
No hope for observing in North Carolina right now, it's raining and expected to be at least partly cloudy for the next week. It's becoming iffy in my backyard for observiing Sirius - only 2-3 hours before it sets behind the trees. I'm beginning to plan other targets. It appears that the immediate areas around other bright, nearby stars have not been explored well recently. Hopefully I'll get a few more attempts this season.
I noticed there is another Sirius A B thread developing with some more photos posted -planning to check that out.
Regards and Clear Skies,
Thad
Quote:
Originally Posted by Vince G
G'day Thad,
I haven't been able to identify it yet either. I use TheSky6 Pro, but it isn't shown, even with the UCAC catalogue.
I'll try and get a better image tonight and do astrometry on it.
You're taking good shots with your gear.
If you want a free sky chart program, have a look at Cartes Du Ciel at
>www.stargazing.net/astropc/< it is supposed to be pretty good. If you get some catalogs you may find what your looking for.
Still cloudy here. Planning another attempt to capture the Pup and look around the nearby starfield, but don't expect even a chance for clear skies for several days.
It looks like this thread has been inactive for a couple of years - but I'll see if anyone is listening.
First I want to thank you all, particularly Dennis, Vincent and Petra for your assistance in my quest of Sirius B and other nearby objects. After some modest equipment upgrades and alot of practice I finally succeeded in imaging Sirius B this Saturday. I will try to attach my 4x image taken from a 640x480 stack of 2900 webcam frames shot at 1/10ths. If I can't recall how to attach the photo, I'll go ahead and post this note, then come back later with the picture.
Once again I and the members of my club (Cape Fear Astronomical Society) greatly appreciate contact with our Australian counterparts in the ASAW.
Thad C.
Wilmington, NC, USA
Last edited by Thad C.; 24-11-2010 at 10:33 AM.
Reason: add photo
Well that looks like a definite split. During my attempts at splitting A & B, I had several false calls where it was difficult to determine if I was seeing an optical or atmospheric artefact rather than the Pup, but all those indeterminate attempts never showed anything as clear as your image does.
Well done!
Cheers
Dennis
PS – how high does Sirius get from your observing spot?
Thank you for your kind comments, Dennis, it is great to hear from you!
The increased separation of the pair has clearly contributed to this little victory. But arranging the image of primary star toward the West (but somewhat South) at the edge of the mirror (thus being sure the perpendicular diffraction spike coming off the mirror edge does not go due East and overwhelm the Pup) is what I think really did it. I bet you'll have good luck if you try this.
I have never really thought about the altitude of Sirius above our horizon. A good indicator is that only in February evenings do we get to glimpse Canopus which just barely clears the tall pine tree tops. I have judged our horizon at these times at about -54 degrees declination. Since Sirius is at about -16deg, it should be 38 degrees altitude. That seems about right, I'll check it next clear night. How about for you?
