Imaging NGC7380 in Ha - Got nothing!! Why?

[swag72]

Last night set everything up and decided to have a go at NGC7380. I had my Ha filter on my DSLR, hoping to get some nice mono shots. Well, in 1020sec subs, I got nothing!!

Does this nebula not show in Ha, or am I just having a total nightmare with this damn Ha filter and need to get back to basics?!!

[Uranium235]

The wizard nebula is mag 7.2, personally I found the Ha a bit of a slog to pick up with a DSLR on this target, and that was with no Ha filter.

Try going for something a bit brighter and easier to test it, the pelican would be a good choice. The seeing might have also affected your data, tonight or tomorrow night looks like a good bet for better results.

[johnrt]

Hmmmm. Something should have showed up - are you sure you were on target?

[antimorris]

Sara - do you have a raw sub you can post of what you got last night? I agree with johnrt that SOMETHING should have showed up in that time.

[shaunster]

Sounds like you missed the target as something even if just a little should have showed up!

[Whippy]

Same here, I've done this object twice and it's definately one of the brighter nebulae I've imaged so with 17 minute subs you should have a fair bit of signal . Post a sub up!

Tony..

[swag72]

If I missed it I just don't know what is happening as I recentred on Vega prior to slewing to NGC7380.

Here's the download of the DSS output file if anyone wants to check. It was 3x darks, 15xflats and about 6xlights at 1020 secs.

Download DSS file output (full size)

Here's 1x 1020 sec sub - Nothing done apart from resize and convert to jpeg.

[steppenwolf]

I suspect that you may have missed the target but for what it is worth, your image is centred on:-

RA 22:50:37, DEC +57:19:44.8

[swag72]

Cheers Steve - I can't understand what is going on with my setup. Since having my nightmare guiding session (that I put down to imaging at zenith and the RA failing totally), I haven't been able to find a single target, despite having centred on vega (successfully) only minutes before. I used the handset, and when I looked on Stellarium it was showing the scope bang on.

I just don't know what is happening with the goto at the moment. Anyone any ideas what I could check?

When I star align (2 star) I often find I am a little out on the first star, but the second on is always on target. I seem to be able to get stars OK, but anything else is giving me big problems.

[steppenwolf]

It could be a slipping clutch perhaps? You are pretty close to the object but I think it is just out of view. It is quite usual for the first alignment star to be out and the second in.

This is what really works for me though:-

I issue the command to go to the first alignment star and when the mount stops moving, I carefully unlock the clutches on the RA and DEC axes and manually push the mount around until the alignment star is in the centre of the field of view and then I clamp the clutches to lock everything in place. It is at this point that I accept the first alignment star. For the second (and third if doing a three star alignment) use the hand controller buttons to centre the alignment star. At the end of the session when I issue the ‘Park’ command, the mount will park to exactly the correct home position all ready for the next session. This means that I always find my first alignment star at least somewhere on my sensor thus greatly speeding up the set-up procedure and ensuring that I have the most accurate 'home' position.

[swag72]

How could I check for a slipping clutch?

Next scenario for the problem is this. I used goto for this target probably around 1 hour prior to taking any subs as the target was behind a hill to start with. So, I couldn't guide and just left the scope tracking for that period. Would this expalin why I have just missed it?

Thanks for taking the time to answer Steve. I do exactly as you said above for alignment - manual for the first star and handset adjustment for the 2nd. I haven't tried park yet as I usually take the OTA off the mount after each session.

[steppenwolf]

All you can do re a slipping clutch is make sure you really have cranked the locking knob up tight.

I used goto for this target probably around 1 hour prior to taking any subs as the target was behind a hill to start with. So, I couldn't guide and just left the scope tracking for that period. Would this expalin why I have just missed it?

This could indeed explain a small part of the 'miss' and it simply not centring the object as you'd have hoped would explain the biggest part of the miss. These GoTo systems are good but not perfect and even with a good alignment, I expect to have to do at least some - albeit small - adjustment to get perfectly on target, normally by taking a 1 minute binned 2 x 2 image to make sure that I can see the outline of the DSO in question and then adjusting the telescopes pointing to suit, often by referencing the brightest star in the image and best guessing where I'd like it to be in the FOV and taking another 1 minute test shot.

[Tim]

Sara, try using three stars around your target as your alignment ones.