Recently Browsing 0 members
No registered users viewing this page.
as well today the sun is shining brightly here. I set up the Lunt to have a look at it, at first just for observing. However, somehow I cannot resist and have to do a sketch This time I've chosen reddish pastels on grey paper to better catch the color of the view in the eyepiece.
Telescope: Lunt LS50THaB600PT
Eyepiece: Celestron X-cel 10mm
Date & Time: May 15th, 2020 / 1400-1430 CEST
Location: home terrace, Dusseldorf region, Germany
Technique: red and orange Koh-i-Noor pastels and pastel pens on grey Canson Mi-Teintes pastel paper
Size: 24 x 32 cm
Clear (and sunny) skies!
I finished observations of the Mizar A spectroscopic binary.
Calibration for the Hα line made on water lines contained in the Earth's atmosphere.
I used LowSpec spectrograph with 1800 grooves/mm reflective holographic grating, APM APO 107/700, QHY163M camera and HEQ5 mount with guiding.
It turned out that the Earth's movement practically compensated for the radial velocity of the Mizar A system.
Based on the analysis, I received the result:
vr = -8.8 km/s
in fact the system is approaching at a radial velocity of -6.3 km/s.
I also determined the phase plot of radial velocities based on my measurements for the Na (together for both lines) and separately for Hα line:
Error is based on half my spectral resolution (0.2 Å/pix corresponds to rv = 10 km/s). Each measurement corresponds to the stack a few images.
The most important purpose of observing this binary system was to record the historical Ca II line (often called as CaK, 3933.66 Å).
The distances in the violet part of the spectrum are almost 2x smaller than the corresponding shifts for the Hα line. This line initiated the discovery of spectroscopically binary systems, and Mizar A was the first discovered system of this type.
These were the spectroscopic observations in the 19th century:
I've made several observations of this line in the last two weeks:
Animation showing the changes in the CaK line based on my observations:
Not only the Ca II is split, but the surrounding lines also, shown below in a wider environment:
Balmer hydrogen lines are becoming more dense as Balmer's gap approaches (3646 Å).
Observation result of the Hα line:
And animation showing the changes in this line:
The Na I doublet was much more difficult to observe, because stars with A spectral type contain very faint lines of this metal:
Animation showing the changes in the sodium doublet:
We received the sodium quartet
1. Alcyone (Eta Tauri, η Tau, 25 Tau) in the Pleiades open cluster, spectral type B7IIIe+A0V+A0V+F2V.
This star is a multiple system, but my goal of observation was the H-alpha profile of the main component:
Horizontal axis scaled to radial velocity:
2. Pleione (28 Tau, BU Tau) also in M45, spectral type B8Vne, variable star, the brightness changes in range: 4.83 - 5.38 V.
This is the faintest star, which I observed with using APO 107/700 & Low Spec spectrograph 1800 l/mm.
It was difficult, but obervation was positive (high gain, exposure time 4 min):
3. Tianguan (Zeta Tauri, ζ Tau), spectral type B1IVe+G8III: (mark ":" according to the VSX database means uncertainty).
This is an eclipsing binary with variability type E/GS+GCAS, period is 133 d. The brightness changes in range: 2.80 - 3.17 V.
4. Cih, Tsih (γ Cas), spectral type B0.5IVpe, variable star with a magnitude range of 1.6 to 3 V:
5. Alnitak (Zeta Orionis, ζ Ori), spectral type O9.5Ibe+B0III. Variable star with a magnitude range of 1.74 to 1.77 V.
Spectral lines have characteristic P Cygni profile, below H-alpha:
I recently upgraded to a purpose made astro-camera (Atik Horizon Color). The learning curve has definitely been noticeable, but I cant figure a couple things out. For some reason the pictures are grey scale when using N.I.N.A. I have tried different binning and formats, but the image is always black and white.
If I use the ATIK software (Infinity,Dusk) there is an option for 'Color Binning', and that seems to have fixed it for those programs, but N.I.N.A doesn't seem to have that option (you can not select anything for binning, or select 1x1, 2x2 ect.). But what makes it weirder is that the preview is always color using N.I.N.A. I used a pinhole lens cover to take pictures of my computer screen and it always shows up as color images. However, if I take that exact image file that previews in color and move it to pixinsight, it is grey-scale.
Is this a binning thing, file format problem? At this point I am just confused, if the preview of the image is color shouldn't the image data be color as well?
So far all the problems I have had with this camera have just been simple things that were new to me, but this one is really throwing me for a loop. Thanks for any help.
I've attached a couple images. The first you can see the NINA preview is color, as well with the couple other I took in the bottom right. And the other in a photo of trying to color saturate the stretched image in Pixinsight, and it says that it cannot saturate a grey-scale image. I have tried this with Tif, Fits, and various binning types.
I scrapped all the Oiii and Sii data I previously took during a full moon (about 15 hours worth) and retook it all when the moon was a bit smaller at 76%. Ha was taken during 98% and 67% moon. All the lights were taken on the following nights: 12th, 19th and 20th September 2019.
Integration times, all in 600s subs unbinned:
Ha = 28.33 hours
Oiii= = 5.67 hours
Sii = 5.67 hours
The Ha data is really nice, and unsurprisingly the Oiii and Sii is not as strong (or nice).
I'm missing that (vital) step in my processing routine of getting the Sii and Oiii properly stretched to match the Ha, before combining. I dont really know how to deal with the weaker data properly. Any pointers would be appreciated.
What I do currently:
All the data is loaded into APP into separate channels/sessions.
The data is stacked and registered against the best Ha sub
This produces individual stacks of Ha, Sii and Oiii that are all registered
Each channel is processed with DPP in APP and then saved as a 16bit TIFF
Each is opened in PS
Stars removed with AA and any remnants removed and tidied up
I then open a blank RGB document in PS
I paste Ha into Green, Sii into Red and Oiii into Blue
Adjust the selective colour settings to get 'Hubble palette'
Adjust levels, curves, saturation until looks ok
All the Ha Sii Oiii data is then combined together in a single 'super' stack in APP using quality weighted algorithm to create a 'luminance'
That luminance layer is adjusted using levels, curves, and NC tools such as local contrast enhancement and deep space noise reduction (using masks to apply as required)
The luminance is pasted onto the above colour layer, and incrementally added using gaussian blur
Cropped and saved.
Here it is anyway I haven't intended on any more exposure time for this one, but will consider it, if the expert opinion dictates otherwise!