Mosaics

[OneCosmos]

Hi,

I have the Mosaic function available as an extra in Sequnece Generator pro. It looks reasonably intuitive - essentially draw a rectangle around the area of sky you want to image and it will calculate whatever is required - great, but it needs a wide field FIT file as a starting point.

Can anyone provide a link to download some widefield FITs of different regions of the sky?

Chris

[Atmos]

Within SGP it can download the regions that you're planning on imaging. For instance, you can just select that you want to do NGC 2070 (Tarantula Nebula) and 4º of the sky and it will download an image for you to draw on.

[troypiggo]

Assuming you're connected to the internet, as Colin says, just type in target name and hit "fetch" I think the button says.

[gregbradley]

Why all the complexity? I have done several mosaics and you simply start somewhere and make sure the next panel overlaps by at least 20% and off you go.

Mind you once with a large mosaic I was left with a bit of a gap between 2 panels!

But for 4, sure do all that but don't get lost in the technology. That's really my message. Sometimes this hobby is made overly complex and it simply a barrier to getting things done.

Greg.

[codemonkey]

Holy ****, that's awesome. I knew that the mosaic wizard existed, but never looked into it or thought about how it worked. To be honest I tuned out after reading "mosaic" because I never do them. I just got the trial of that plugin for my existing copy of SGP, and I'm in love with this feature. It's going to make framing so much easier, even for people like me that don't do mosaics.

[troypiggo]

It's pretty cool, hey. And simple. Just a few clicks to set up a mosaic of any size and number of panels. I can only assume from Greg's comments above that he hasn't used it ;)

[Atmos]

It does sometimes have its pitfalls when you realise that you need to do a 16 panel mosaic to fit some objects in in their entirety :P

[OneCosmos]

Apologies for not getting back to this sooner - I actually forgot to check!

Thanks to everyone who replied and yes, the 'fetch' option works fine. I did see that actually but in the object drop down it said no objects in cache and for whatever reason it just didn't cross my mind to type something in that field like M42 and click fetch. Sometimes things really are as easy as they look!

Yes, it is totally brilliant and think I will devote Astrofest this year to mosaics. I suppose once I have some data of a wide field through the 152mm refractor I will then be posting about how to process a mosaic :)

Chris

[tim.stephens]

Have to agree - brilliant tool and don't see why it isn't included in the standard purchase. Even if you want to take a single image and not a mosaic, once you plate solve it picks up your camera rotation and allows you to frame the image perfectly.

I still have Cartes, but now I really don't see myself using it as much as before.

Started a 9 panel mosaic of 6188 last night. Got half of the HA panels before the clouds rolled in. Has added a whole new dimension to photography for me!

Tim

[OneCosmos]

I presume you can build up a cache because obviously at Astrofest we have no Internet connection. I will plan a whole bunch of mosaics before then. I've had the tool since last year actually and just never got around to using it.

This year is different for me though because it is the first year I've had an observatory which means I've had lots of practice which is great. Normally, having not used the equipment since the last AF the first night is wasted trying to remember how to use all the software :(. That puts mosaics firmly on the radar for this year and in general from the observatory moving forward.

I remain puzzled about how one stitches them together in the processing though, although I am guessing, as with so much else, the software just does it automatically :)

Chris

[troypiggo]

For Astrofest, I'm considering doing something similar - planning ahead some mosaics, doing the fetch and creating some plans ready. There is an option to save the fetched image as reference if you want.

[peter_4059]

Does it remember the cached images or do you need to save them as a reference? It would be nice if there was an option to fetch and cache all the images in your current plan.

[Atmos]

It does kinda save them, although the image doesn't get saved you can save the object coordinates to your target.

[troypiggo]

It seems to attach the images to the plan. You don't save them to a file location per se. I guess that's what it means by caching?

[gregbradley]

Sky X has a mosaic tool built in as well. You can click on a panel and it will go there making life easier when its a nondescript part of the sky that you sometimes get when doing a mosaic. That's the hardest part, lining up a part of the sky with no landmarks in it. And then later when processing if you have a lot of panels, nondescript parts of the sky are hard to orient in place. Like a jigsaw puzzle so labelling them with a grid pattern helps.

Greg.

[Atmos]

I have looked at the mosaic thing in TSX, found SGP one a lot easier to use and arguably more useful as it actually downloads a picture to give you as reference. I found it mostly useful when looking at some of the brighter nebulae.

[OneCosmos]

So, although I have no raw data yet for a mosaic, I'll ask now anyway. How do you process them? My understanding is that in SG Pro calculating a mosaic results in multiple separate subjects, with their own coordinates of course and you just schedule x number of subs for each one just as though they were really independent subjects. If so, you then just end up processing x number of images but how are they then stitched together?

I would imagine though the stiching must be done early on in the processing, whilst still in linear format at least because each will need almost identical processing if it is to really look like one image.

I use SG Pro for stacking - can I also use it for this stitching together?

Chris

[vlazg]

I didn't know you could stack with SG Pro, where is it?
You can use PS6 under Files - Automate - Photomerge just make sure they are fairly similarly stretched

[troypiggo]

You can't stack in SGP. "Stack" referring to the individual sub integration process. SGP mosaic wizard will create a plan for you, with a target for each panel. Each target contains the coords for each panel, and you need to tell each target how many subs, which filters, exposure times etc.

Chris - yes, you need some other image processing software to merge the panels captured in SGP into a mosaic. PixInsight, PS etc.
There's a good tutorial for doing mosaics on PixInsight here: http://www.lightvortexastronomy.com/tutorial-preparing-a-mosaic.html
Can't recall if you're using PI or not, so apologies if not.

[OneCosmos]

Doh, I didn't mean I stack in SG Pro sorry, I stack in Pixinsight. The link will be very useful - thanks.
Chris

[OneCosmos]

I have just taken a quick look through this - can't wait to capture some data to try it out. The Veil is a little too low to bother at Astrofest - but I could capture the Cat's Paw and Lobster together. I did take this with @380mm with the Meade 80mm and both are in the frame but of course it isn't as detailed as I could get with the 152mm @900mm using a mosaic.

Chris