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Old 30-12-2008, 12:34 PM
Ian Robinson
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How deep ?

What's your best estimate of the deepest you've managed to go (magnitudewize) with your telescope and digital camera or CCD on fuzzies , and on stars ?
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Old 30-12-2008, 02:30 PM
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21 with CCD current set-up. 12"
17 with 300D 10"
15 on 400ISO film 10".
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Old 31-12-2008, 08:42 PM
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That's kinda about what I thought.

+15mag with an 80mm refractor mentioned elsewhere must be a typo.
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Old 31-12-2008, 10:17 PM
Dennis
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Inspired by Jeff's recording of Sycorax (a moon of Uranus), I managed to record down to Mag 21.86 with a Celestron C9.25 at F6.3 with an SBIG ST7E CCD camera using 30 minute sub frames, shot from suburban Brisbane (7kms from CBD).

Using my Vixen 4” f9 refractor and SBIG ST7E CCD camera, with 15 minute sub frames, I have recorded stars down to mag 19.18.

Cheers

Dennis

Last edited by Dennis; 31-12-2008 at 10:40 PM.
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Old 31-12-2008, 10:55 PM
Ian Robinson
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Quote:
Originally Posted by Dennis View Post
Inspired by Jeff's recording of Sycorax (a moon of Uranus), I managed to record down to Mag 21.86 with a Celestron C9.25 at F6.3 with an SBIG ST7E CCD camera using 30 minute sub frames, shot from suburban Brisbane (7kms from CBD).

Using my Vixen 4” f9 refractor and SBIG ST7E CCD camera, with 15 minute sub frames, I have recorded stars down to mag 19.18.

Cheers

Dennis
That's pretty deep drilling .... with such small scopes .
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Old 01-01-2009, 07:45 AM
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One difficulty in determining the magnitude of fainter stars is that the USNO-A2.0 Catalogue (a catalogue of 526,280,881 stars) “only” goes down to around mag 19. It was a 6Gb+ download!

To go dimmer than mag 19, I use the USNO Flagstaff Station Integrated Image and Catalogue Archive Service which is based on the POSS-I (1st epoch Palomar Obs. Sky Survey) and POSS-II (2nd epoch Palomar Obs. Sky Survey). The data lists the Red and Blue magnitudes.

Cheers

Dennis
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Old 01-01-2009, 09:04 AM
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With 120mm F5 achromat and GStar camera I get occasionally to 17 magnitude (150 stacked exposures). I’m in very light polluted location.
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Old 01-01-2009, 02:26 PM
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I've used the A2 catalogue on occasion.
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Old 01-01-2009, 04:24 PM
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Never measured.. But would like to learn how.... Dennis, I might be picking your brain a bit at Astrofest this year! (again!)
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Old 01-01-2009, 08:26 PM
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When Peter Marples discovered his S/Nova several months ago, we observed it on a 17 inch LCD using a Mallincam video camera on a 12 inch LX200R at F7 when it was at 17.5 Mag using 14 second intergrations and maximum gain, in light polluted brizzy through some thin high level cloud. It was bright and a Mag 18.5 star was there as well.Pity about the cloud as we had to pack up just after we managed to view it for about 3 minutes before it clouded in for the next 3 bloody weeks so we were unable to chase it again. We confirmed this detection with Peter using his star charts. This camera can get to Mag 21 in 56 second intergrations using 10 inch scope and dark skies as what has been done overseas with no stacking or processing. So mag 15 using a good quality cooled CCD camera or astro video system and an 80mm scope is very possible.

Regards Matt.
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Old 05-01-2009, 12:04 PM
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Mag 22.5 for me (ST7-ME on 12" LX200 classic), a couple of years back now. That was the mag of the 13th brightest galaxy contained within the Hubble Deep Field South, and I captured 13 galaxies definitely, a few more debatable, so that's how I determined the 22.5 limit.

Roger.
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Old 05-01-2009, 12:13 PM
Dennis
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Mag 22.5 for me (ST7-ME on 12" LX200 classic), a couple of years back now. That was the mag of the 13th brightest galaxy contained within the Hubble Deep Field South, and I captured 13 galaxies definitely, a few more debatable, so that's how I determined the 22.5 limit.

Roger.
Impressive stuff Roger.

My mag 21.86 effort was of a star, a point source, making it an easier target!

Cheers

Dennis
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Old 05-01-2009, 02:12 PM
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Impressive stuff Roger.

My mag 21.86 effort was of a star, a point source, making it an easier target!

Cheers

Dennis
Thanks Dennis,

I was very impressed at the time and still look back on my efforts and think how amazing it is that amateur astronomers can capture such faint data with such affordable equipment. I have always wanted to try another blank piece of space like the HDFS to see what I can see with the same exposures, see if there's galaxies not yet observed, but haven't got back to it, too cought up in other projects like my NGC photography

Roger.
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Old 07-01-2009, 05:38 AM
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Hi All,
This is an image taken last night. (HH74) 6x30min -darks
The data reduction was done in Astrometrica. (Green circles are reference stars)
The details of the image fit are in the window at the bottom of the image.
To the right is the magnitude estimate of the red circled object. (R=21.0)
I think there are fainter than this.
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Old 07-01-2009, 06:30 AM
Dennis
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Nice work Jeff. At mag 21 the selected object is quite distinct, so I reckon you’ll definitely find fainter stuff on that image.

Cheers

Dennis
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Old 15-01-2009, 02:22 PM
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Originally Posted by theodog View Post
Hi All,
This is an image taken last night. (HH74) 6x30min -darks
The data reduction was done in Astrometrica. (Green circles are reference stars)
The details of the image fit are in the window at the bottom of the image.
To the right is the magnitude estimate of the red circled object. (R=21.0)
I think there are fainter than this.
I don't doubt that you can reach mag 21, and reaching mag 21 is great however just a word of caution in case you are not aware: I remember trying to estimate my limiting mag in Astrometrica and when I read into it I discovered that for those "edge of detection" point sources like that the estimation is not more accurate to about +/- 2 mag. It was a while ago, and I can't remember the specifics.
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Old 15-01-2009, 03:00 PM
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I don't doubt that you can reach mag 21, and reaching mag 21 is great however just a word of caution in case you are not aware: I remember trying to estimate my limiting mag in Astrometrica and when I read into it I discovered that for those "edge of detection" point sources like that the estimation is not more accurate to about +/- 2 mag. It was a while ago, and I can't remember the specifics.
Geez it may be 23!

Thanks for the word of caution Roger, well heeded.

I am, however, careful to check with other methods for any measurement. I have included a screenshot with Guide 8 to demonstrate the depth reached in the image.

I have no problems with Astrometrics, nor it seems do the MPC as I have not been q'ed regarding my estimates made with Astro..

Further, a professional Astronomer who shall remain nameless, yet has several asteriod discoveries and comets, did indicate that this program is reliable.

However, I get the point that one can't be overcautious in interpretion of data.
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Old 15-01-2009, 03:29 PM
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Geez it may be 23!
funny... that's exactly what I thought when I read it (whenever that was), "oh cool, could be +2 fainter!!"

Quote:
Originally Posted by theodog View Post
I am, however, careful to check with other methods for any measurement. I have included a screenshot with Guide 8 to demonstrate the depth reached in the image.
Interesting to see how to get another comparison. At the time I didn't know any other way to get an estimate so I just moved on, I can't remember what the figure was that I was trying to confirm, something like mag 21 like you.


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I have no problems with Astrometrics, nor it seems do the MPC as I have not been q'ed regarding my estimates made with Astro..
Ahh, very good. I'm in awe of people who actually get to the point of submitting something to the MPC ... I got half way there but it was a big leap to actually have something sure enough to send to MPC so combination of things I moved on to another project
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Old 15-01-2009, 04:26 PM
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Cheers Roger.

Give MPC another go. The chase is as much fun as the catch.
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