M101 - May Challenge from Kent UK

[Graeme1858]

Set up last night to capture some M101 data for the challenge. After waiting for the sun to go down I got set up and aligned and grabbed some M104 whilst waiting for darkness. So I slewed to M101, took a few frames to plate solve, compose and get the exposure right and started PHD guiding. Then I set an APT plan going for 9 x 420 second lights and went indoors for a kip on the settee! I set the alarm for an hour later, woke up and went out to see how things were going. Guiding and capturing were still fine but the clouds had completely covered Ursa Major! I managed to salvage 4 frames and 2 matching set up frames. M101 was 10º past the meridian by now and I purposely left the mount running to see what would happen! My CGX mount can go 20º past the meridian and I've never done a meridian flip. I need to look into how APT controls a flip if I'm going to aspire to move on and start doing greater than 1 hour exposures! Anyway, I did just 5 darks, 'cos it was late (deja vu!) 50 bias and 50 flats.

Stacked this morning using DSS and processed in Gimp. There's some banding but overall, lack of data considered, I'm somewhat pleased.



Regards

Graeme

[Larry 1969]

First, nice M101! Thanks for sharing!

I've considered the meridian flip as well but I came up with this approach and it works well enough for me... Maybe give this a try?

As my target approaches the meridian, I park and cover telescope and shoot dark and bias frames... This takes long enough that my target is past the meridian so I just get back on it and chase it down.

Larry

[bobharmony]

Nice M101 with so little data. This is one target that really benefits from a lot of exposure time!

About APT and the meridian flip, it is a little confusing to figure out the settings but it works very well once all of that gets figured out. The plate solving that occurs after the flip frames the target beautifully, just a few pixels at most off from the pre-flip frames. These are the settings I use for Session Craft to manage the flips:

The negative number in the "Flip Moment" tells APT to do the flip 5 minutes after passing the meridian, along with leaving the "Delay is counted after meridian flip" box UNCHECKED. It took me a few attempts to finally get that figured out! Previous attempts had stopped imaging pref-flip and waiting idle for a longer period of time before flipping and resuming the session.

Oh, don't forget to check the "Make Automatic Flip" box when you are ready to go

Bob

[Graeme1858]

First, nice M101! Thanks for sharing!

I've considered the meridian flip as well but I came up with this approach and it works well enough for me... Maybe give this a try?

As my target approaches the meridian, I park and cover telescope and shoot dark and bias frames... This takes long enough that my target is past the meridian so I just get back on it and chase it down.

Larry

Sounds like a nice simple strategy. I'll give it a go.

Then is it just a case of flipping the post meridian images so they all match before stacking?

Cheers.

Nice M101 with so little data. This is one target that really benefits from a lot of exposure time!

About APT and the meridian flip, it is a little confusing to figure out the settings but it works very well once all of that gets figured out. The plate solving that occurs after the flip frames the target beautifully, just a few pixels at most off from the pre-flip frames. These are the settings I use for Session Craft to manage the flips:

The negative number in the "Flip Moment" tells APT to do the flip 5 minutes after passing the meridian, along with leaving the "Delay is counted after meridian flip" box UNCHECKED. It took me a few attempts to finally get that figured out! Previous attempts had stopped imaging pref-flip and waiting idle for a longer period of time before flipping and resuming the session.

Oh, don't forget to check the "Make Automatic Flip" box when you are ready to go

Bob

Thanks Bob. What is the reason it needs to do a Blind Solve if it knows where it's looking? I ask because I'm usually ok with the Solve function after selecting the imaged object from the APT database but I've not managed to get Blind Solve working!

Regards

Graeme

[Larry 1969]

Sounds like a nice simple strategy. I'll give it a go.

Then is it just a case of flipping the post meridian images so they all match before stacking?

Cheers.

It works well enough for me and no. No need to rotate your images before stacking. DSS will handle that.

Good luck!

Larry

[bobharmony]

Graeme - I use blind solving because All Sky Plate Solver seems to work faster for me than PlateSolve2. Whatever works for you should be fine.

And a +1 for DSS handling the stacking of pre- and post-flip images. Nothing special needed, it just handles them.

Bob

[Gerald_db]

I use N.I.N.A. for capture with ASTAP for plate solving and blind solving and its flawless. Friday night I ran into a meridian after 15 images of M83. I had switched on the auto flip function a while ago but never needed it. It was perfect. Fully automated, stopped imaging and guiding, flipped, stabilised, auto plate solved, re-framed, chose new guide star, started guiding and imagining. My only problem is I'm not sure how to deal with the 5 post flip images that are inverted when I get to stacking with PI.

[Juno16]

Nice M101 with so little data. This is one target that really benefits from a lot of exposure time!

About APT and the meridian flip, it is a little confusing to figure out the settings but it works very well once all of that gets figured out. The plate solving that occurs after the flip frames the target beautifully, just a few pixels at most off from the pre-flip frames. These are the settings I use for Session Craft to manage the flips:

session craft JPG.JPG

The negative number in the "Flip Moment" tells APT to do the flip 5 minutes after passing the meridian, along with leaving the "Delay is counted after meridian flip" box UNCHECKED. It took me a few attempts to finally get that figured out! Previous attempts had stopped imaging pref-flip and waiting idle for a longer period of time before flipping and resuming the session.

Oh, don't forget to check the "Make Automatic Flip" box when you are ready to go

Bob

Very interesting values in Sessioncraft Bob. I started having issues with the meridian flip when I started messing with the default values because the default values ate up so much imaging time. I just turned the AMF off and do a bright star focus at flip time.

Now that I have a focus motor, I will hopefully go back to using the AMF. Thanks for posting your values. I’ll give them a try!

[BABOafrica]

Nice image even with the banding. You captured some good detail there.

BABO