Difficulty with LhiresIII H-Beta calibration-2400 l/mm Grat

[James Foster]

I've collected Hb spectral data for R Aqr, Vega, gam Peg, and other objectrs this last week, but have been struggling with Ar-Ne line identifications
in my -neon.fit files. I had no issues with this on my L-200 spectroscope (using the Alpy calibration module) but identifying the lines generated
by the LhiresIII seems more problematic. After numerous failures (identifying the lines) in Isis, I went to Bass Project V 1.97 to generate the Ar line identifications:

This seem to bring the H-Beta wher is "should" belong. However, these line are not the main (brightest) lines and Isis will probably have a hard time identifying.

Just for info and possible calibration by others here, here is some of my data:

http://www.astroimage.info/spectra/Lhir ... 441m-5.tif
http://www.astroimage.info/spectra/Lhir ... neon-1.tif
http://www.astroimage.info/spectra/Lhir ... neon-2.tif

1st is a 15sec exposure of Vega centered on Hb (micrometer reading 1441)---RENAME .tif to .fit after download
2nd is 3x30sec exposures of the Ar-Ne lines before exposure.---RENAME .tif to .fit after download
3rd is 3x30sec exposures of the Ar-Ne lines after exposure.---RENAME .tif to .fit after download
I also enclose a .lst file for the Ar-He lines that seem to work in Bass:
http://www.astroimage.info/spectra/Lhir ... es/Hb6.txt
---RENAME .txt to .lst after download

The main lines almost look like a 2nd order Ne lines, but I haven't been able to get a good calibration file generated to make Isis correctly identify the right lines.
If you have a better line identification chart for this Hb area and better yet a .lst for the line it would help alot!

James

[Ken Harrison]

James,
I've sent you copies of the argon/ neon reference data files I use in BASS Project. May be helpful.

[Paul Luckas]

HI James,

Attached is what I use for H-beta with my Lhires + 2400 + relco (note, there are variations in these bulbs). I hope it helps.

Also, Manfred Schwartz has a wonderful resource on his web site which I'm sure he won't mind me sharing:

http://www.astrophoto.at/calibration-arne.html

Paul

[James Foster]

Thanks Paul & Ken,

My Alpy calibration module's Ar-Ne lines resemble the Relco lines in Manfred's images.....i wonder why the LhiresIII Ar-Ne images I got for this region look so off...like somekind of 2nd order leakage from the Ne set longer-wavelength than 5000A. Any way I retry Isis with these.

James

[Peter Somogyi]

Hello James,

Here is my 2x2 bin config for the ATIK 428 for H-beta, I think you can just copy/paste (and later extend with more lines for your ATIK 460 for better accuracy to your chip's edges):

2
0.15352182952182952182952182952183
4806.020
4847.810
4879.864
4889.042
4904.752

You can identify 4847 via looking at ref.star's H-beta place by pixel (read its position first displayed in ISIS), and move to the left next prominent line after switching to the calibration image. I am taking 17 seconds calibration image here, as some of the included lines are weaker.

Peter

EDIT: my cal. image (Ar/Ne) almost matching with Pauls except having a few extra blended lines to the right. My bulb is from an extra ordered batch from Shelyak, and I do remember there are slight differences to the older one, but not much.

[James Foster]

To: Peter,

That did it! Using your provided line numbers and my previously calculate dispersion I got this (Processed Isis V5.9.0):

Here is the .lst file numbers I used:
2
0.112438486
4806.020
4847.810
4879.864
4889.042
4904.752

Will process the R Aqr, CH Cyg, gam CAS, CH Cyg, etc Ha & Hb spectra I've taken over the last week....thanks again!

James

[Paolo Berardi]

Hi James,

Ken, Paul and Peter already give you valuable advice. I would just add one because the Vega H-beta profile you showed above hasn't even correctly calibrated (indeed, the narrow Fe absorption line on the right of H-beta line should be at ~4923.9A, in your profile it is at about 4909A).

Please always check the calibration RMS value that ISIS returns at the end of processing (tab GO output window). A very small value is an indication of good calibration (using a number of lamp lines greater than the polynomial degree).

Let us know,

Paolo

[Paolo Berardi]

Hi James, I show you the "calibrated" lamp spectrum. Maybe it is useful to perform a further check (very strange!)



I do the opposite, that is I roughly calibrate the vega profile with the small absorption lines and H-beta (RMS = 0.039A), then I calibrate the lamp spectrum with the same polynomial. So I assumed there is no lambda offset or reversing between the frames.

Paolo

[James Foster]

To: All,

Thanks for all the great advice! The deeper into spectoscopy I get, the more I realize how little I actually know/understand! Since I was having a little more success with my
Hb thanks to the extensive advice from here, I went a step further and downloaded and normalized the Elodie3.1 medium resolution (R=10000) of Vega for the range of Hb I
was shooting at (4786-4940 A). Here's the generated IR using the comparison, then continuum function of IS:


I needed to shift my Vega spectrum relative to the Elodie Vega spectrum -0.026A to get a good line-up. Using this curve as my IR, I reprocessed Vega Hb and compared is to the Elodie:


Is this a satisfactory result? I know I should have eliminated the tellurics, before processing the IR, but I wanted to try and get a "good" IR as an exercise before processing my
other H-Beta spectra.

James

[James Foster]

SEE NEXT POST-Hb Correected finally!

Hi James, I show you the "calibrated" lamp spectrum. Maybe it is useful to perform a further check (very strange!)



I do the opposite, that is I roughly calibrate the vega profile with the small absorption lines and H-beta (RMS = 0.039A), then I calibrate the lamp spectrum with the same polynomial. So I assumed there is no lambda offset or reversing between the frames.

Paolo

To Paolo,

Thanks for noticing the Fe out of balance with the published value. Per your instructions, I went into Bass 1.97 and calibrated on the Hb and Fe lines and then proceeded to see were the Calibration lines went; NOTE: the Hb was slant corrected, selected, and smile correction was applied to both from the Ne-Ar calibration file:


As you can see, none (with the exception of Ar 478.9nm) of the calibration lines, line up when calibrating against the expected positions of Hb and Fe. I guess I'll have to limit my LhiresIII use to Ha at this point until I can make sense of thr LhiresIII Ar-Ne sequence around Hb. My calibration lines for the L-200 (using the Alpy calibration module) were much simpler to analyze and calibrate against...see:



James