I’ve been playing with the mosaic wizard in preparation for a trip to Queensland Astrofest. There is no internet coverage at that site so I figure I’ll need to cache any mosaic wizard reference images I plan to use while I’m there. I tried do get a 4deg field around NGC6334 however the downloaded image is very washed out to the point that the nebulosity is impossible to see for framing purposes. By comparison the images Astroplanner downloades as reference images are quite detailed. Is there a way to improve the framing and mosaic wizard cached image quality?
Can you adjust the histogram in the F&M wizard image? When I get an image
like this I usually just need to stretch the image. Sometimes the image
downloaded doesn’t match the named image, but when I put in the actual RA
and DEC coordinates rather than the object name the right image comes up.
However it does look like the correct coordinates are already in the wizard.
Joel. I’ve tried stretching the image using the black and white point sliders howerer, looking at the histogram, the dynamic range of the downloaded image seems to be heavily compressed so it doesn’t stretch very well. I can just make out the lobes of the cats paw so I think it has downloaded the correct image and as you point out the coordinates match. NGC6188 is another part of tje sky where this same issue is present.
I’m not entirely sure where AstoPlanner gets its images or if they’re curated. I’ll see if there are options on the service to pull “deeper” images but I don’t believe there is.
Yeah there appears to be something wrong with 'the image downloaded. I’ve
never seen a histogram like that with a SIMBAD image using the Framing and
Mosaic Wizard. Here’s something else to try. Shift the coordinates a
little bit, and/or increase or decrease the FOV and see if the image
downloaded looks the same.
I’ve had similar experience to Peter recently. Washed out image, different targets so not sure if shifting coords will help. I believe AstroPlanner’s images are downloaded from POSS, Palomar Quick-V Survey, HST Phase 2, and SDSS for selected areas. You can set which ones you want to use in the preferences. Most of mine, and looks like Peter’s above, are from the HST source.
To get around the “washed out” image problem, I’ve tried using images downloaded from web, but the SGP framing wizard seems fussy about what images it’ll accept. Looks like only 16 bit FITS with RA/DEC coords in the headers. Would be handy if it would allow, say, JPG files downloaded from web or whatever, you could plate solve them and save as FITS with headers needed etc.
Reading from the Astroplanner user manual, it has the ability to download images from the first or second generation Palomar Digital Sky Survey (DSS) or colour images from the Sloan Digital Sky Survey (SDSS). I think there is also an option to get HST images. Most of the ones I’ve downloaded are “1deg x 1deg 2nd Gen All Sky Red”.
Even if there was more information on what headers and FITS format SGP is after for these reference frames, we could generate our own.
Troy, I don’t think it will let you generate your own reference image - it still seems to download one even if you provide an image when you click the fetch button. I get the impression it is just using the image you provide to get the RA and DEC coordinates for the centre of the download.
Just wondering if there has been any update regarding the quality of images downloaded for use with the mosaic tool?
I have tried adjusting the FOV, co-ordinates and adjusting the Histrogram but it is difficult to make out any objects in some images.
Not as of yet. I’m currently looking at adding other survey suppliers that may have deeper data. No ETA as of yet.
I think ideally we may want to:
- Add the ability to provide your own image, solve it and use that as the “source”
- Look into additional survey providers
Either of those options would be a great improvement. Can’t wait.