Two 1x3 Mosaics of M8 and IC1396

Hey Martin

Thanks for the suggestion.  they are both fine targets I am happy to go with the thoughts of the syndicate

Do these targets play to the strengths of the kit on pier?  When do they rise?  Are they going to be difficult to schedule?

Are we going to fall foul to a probelem like the  orion mosaic last year when it was ordered 3 months too late so it was rising at midnight rather than at 4am.

The lagoon shot looks fab, but it encompasses only 90% of the object.  Would we be better choosing one frame of particular interest in the knowledge that we wont get the whole object unless we acquire a 4x2 mosaic? Is there a particularly interesting bit that we could commit to ( much like I tried to get on pier 1 with the whisps of orion rather than its core)?  Since this object is in the south - it is going to be hampered by the moon so even narrow band will have to be acqured when the moon has set.  is the entire lagoon a better pier 5 or 14 target?

I must admit I though about the elephant trunk especially the easter section...  it is in the north so it is easier to acquire.   Are there other parts of the ares, such as the bok globules to the north  that might as interesting as the trunk?

Paul

Thx Paul for the reply and multiple questions.

WhileNoMoreCloudyNights pointed out the new altitude limit of Pier 9 I have to admit that M8 ain´t raising high enough at the moment. So we have to put that one on hold.

IC1396 on the other hand is up pretty high, so that would work just fine right now.

According your other questions for interesting details within nebulas: I assume you want to answer that yourself and also suggest some new targets? :-)

CS

Martin

Just recognized that Anonnuki added RGB data request for the elephant trunk 1x3 mosaik in order to get color data for the stars (i assume from the descriütion?). Jobs 2269 ff.

I´d like to question the necessity of this job request, while you can easily calibrate the star colors with the already requested HSO dataset. Almost any astro imaging SW nowerdays support that features.

For the nebula itself, being an emission nebula, RGB data is not adding new valuable information to it.

Thus, it seems unnecessary for me to get this data by spending multiple hours of scope time of Pier 9?!

Your thoughts?

Hey Martin,

Calibration is one thing, but you still wont get the same star colors out of NB filters as you will out of RGB, and I prefer the latter...

RGB requests are for 100 minutes per panel, so 5 hours total, which takes the total time for the mosaic from 24 to 29 hours...

I agree that the RGB stars wont make the resulting image 20% better for all users (maybe just me lol), so if you feel strongly about it you are welcome to DM the admins to request removal of the submissions - you have my blessing :)

I think the trunk was well framed by the way, should be a great shot!

CS, Annunaki

Annunaki

Seeing as the narrowband version has been agreed as a 3 panel then who are we to argue about RGB stars if you want it, It would be very churlish of Robo Admin to do so :)

At least you kept them a sensible sub length and overall exposures per filter per panel was not outlandish, personally on this pier 60mins in red per panel should be more than enough for RGB stars for future. with the other bands being adjusted to suit that

However for the sake of hassle for Pete we will input as is dont worry :)

HTH

Steve

Hi,

just for the learning experience :-)

If I extract the stars form a narrow band image, the color of the stars will be way off due to the narroband filters. If I now apply color calibration (e.g. Spectroskopic ColorCalibration in PI) I would expext the calibration process to calibrate the star colors, so they are being changed to what they are supposed to be in respect to the catalogue colors. I mean that´s the whole purpose of the color calibration, right? If I add the corrected stars back to the starless narrowband image (e.g. via PixelMath) I should get a nice narrowband / hubble pallette nebula image with real RGB star colors?!

So there should not be any difference between the star colors of narrowband or RGB datasets after applying the color calibration?! Am I wrong?

I am curious to know. What´s your experience? Did you ever compare both ways? While we will have all datasets available soon I´ll try to go both ways and compare the results.

CS, Martin

Hey Martin,

I'm no expert on the matter, but I think that colour calibration essentially works by setting a baseline "white reference", and then applying independent histogram transformations to each of the color channels to match the star colors to that white reference.  So if you select a very blue star (eg B0V) as a white reference, the blue stars in your image (as determined by reference to the stellar database) will appear white, and all less blue stars and everything else in the image will be shifted towards orange/red.  Conversely, if you select an reddish star (eg M0V) as white reference, the redder stars will be white and the bluer stars (and non-stellar features) even more blue.  The general recommendation is to use "Average Spiral Galaxy" as the white reference if you are looking for the most "natural" colours, and this is what I generally use.

What colour calibration doesn't do is adjust the individual colours of each star to match what they "should be" based on the photometric database.  It simply works with the data you pass to it, so you will get a different result if that data was acquired on narrowband filters than if it was acquired using broadband RGB filters. 

I have attached two images, one with NB stars and the other with RGB stars, to indicate the difference in the particular case of the Propellor Nebula.  The narrowband data was acquired using S+H+O filters, and combined in a "true colour" fashion, similar to that described in this interesting video from TAIC: https://www.youtube.com/watch?v=cu76vNPq4Tc

I highly recommend you experiment with the all the calibration settings, star layers etc to get a feel for the differences.  You may even want to experiment with deviating from the standard "Average Spiral Galaxy"-type white reference: for example you can really emphasise the blue aspect of a nebula by selecting a red star as white reference.

Good luck, and be sure to report any interesting findings!

CS!