spectro-aras.com

To: Paolo,

RE:"Hi Robin, here's the comparison...."
Can you upload your divided spectrum to BAA so Robin or anybody else can compare directly? His divided Alpha Orion spectrum referenced here:
http://www.spectro-aras.com/forum/viewt ... 433#p13514 has been placed in BAA as well so you can download; you can get
my Alpha Orion spectra from there as well....Cheers!

James

Hi James, nice spectra! I uploaded the original Alpha Ori profiles (six spectral intervals) on BAA database. You find in attachment the Miles division FITS profile I showed in my previous post.

Paolo

Here is my updated trend since the end of last year. The spectrum is still evolving in the 7400A region relative to 2020-01-18

(2020-01-10 was taken using the ALPY 200 so lower resolution, the others are with the ALPY 600 at R~500)

Cheers
Robin

To: Benjamin,

RE:"Integration's limits for EW compuation have to be the wavelength were line cross the local continuum.
That's why Spcaudce computes a continuum for EW computation.
This continuum has a important influence in EW value."


I finally had time to "play" with SpcAudace with some of my LhiresIII spectra of Betelgeuse. Here are the outputs I got when using the terminal command:
"spc_autoew filename.fit 6535 6595"

09Jan19 Data:
# Date: 2019-01-09T08:10:09
# JD: 2458492.8404
# EW(60.00=6535.00-6595.00)=15.165 A.
# Sigma(EW)=2.016 A.
# SNR=17.
# 15.165 2.016 17 2458492.8404 {EW(60.00=6535.00-6595.00)=15.165 A.}

13Jan2020 Data:
# Date: 2020-01-13T06:31:38
# JD: 2458861.7720
# EW(60.00=6535.00-6595.00)=3.858 A.
# Sigma(EW)=1.523 A.
# SNR=27.
# 3.858 1.523 27 2458861.7720 {EW(60.00=6535.00-6595.00)=3.858 A.}
[My SNRs are a little low!]

Do these look right?
Here's what I got using the "ew_courbe" command on the working directory containing only LhiresIII Ha data on Betelgeuse:

When I used a larger range for the EW search with the "ew_courbe" (6510-6596) the EW trend was decreasing width; only 3 data points is probably too little.
I have a lot more to learn about your powerful program......I just need to be less afraid of "Command line terminal boxes!"

James

The measurement is clearly not working correctly as H alpha is obviously always in absorption but the EW on ~58825 is negative ie in emission. Cool stars like Betelgeuse are a very difficult case as all lines are blended and there is no clear continuum.

The spectro Betelgeuse yesterday :
What is the emission ray at 6541 A ?

etienne bertrand wrote: What is the emission ray at 6541 A ?

Is it emission or just the molecular band head surrounded by blended absorption lines? It is so hard to tell with cool stars. You can see the general shape in that region better in low resolution spectra
http://www.spectro-aras.com/forum/downl ... hp?id=6602

About EW measurement with SpcAudace, James worked with spc_autoew.
This is not a good idea here, with such a noisy continuum.
You need here to controle how continuum is fited. This can be achieved with "spc_ew" command that accepts continuum fiting parameters. Usage with examples can be found here:

http://spcaudace.free.fr/docs/index.php ... tml#manual

Note that spc_ewcourbe which built EW=f(t) plot has a third optionnal argument: the polynomial order for continuum fiting.

Benji

To: Benjamin,

Yes I should have used the spc_ew for absorption lines....I did this, but disregarded the results. Here is what I have for my three (3) Alpha Orion spectra taken
with the LhiresIII with 2400 l/mm grating:

09Jan19:
SpcAudance Terminal Comm used:"spc_ew _aoriha_20190109_340.fit 6535 6595 6 n 2"
# Date: 2019-01-09T08:10:09
# JD: 2458492.8404
# EW(60.00=6535.00-6595.00)=1.956 A.
# Sigma(EW)=2.431 A.
# SNR=17.
# 1.956 2.431 17 2458492.8404 {EW(60.00=6535.00-6595.00)=1.956 A.}

11Dec19:
SpcAudance Terminal Comm used:"spc_ew _aoriha_20191211_381.fit 6535 6595 6 n 2"
# Date: 2019-12-11T09:08:51
# JD: 2458828.8811
# EW(60.00=6535.00-6595.00)=0.799 A.
# Sigma(EW)=1.810 A.
# SNR=23.
# 0.799 1.810 23 2458828.8811 {EW(60.00=6535.00-6595.00)=0.799 A.}

13Jan20:
SpcAudance Terminal Comm used:"spc_ew _aoriha_20200113_272.fit 6535 6595 6 n 2"
# Date: 2020-01-13T06:31:38
# JD: 2458861.7720
# EW(60.00=6535.00-6595.00)=0.805 A.
# Sigma(EW)=1.576 A.
# SNR=27.
# 0.805 1.576 27 2458861.7720 {EW(60.00=6535.00-6595.00)=0.805 A.}

Here is a SpcAudance plot of the last spectra showing the "EW Splice:"


Not sure why I'm getting the positive EW values of 1.956A, 0.799A, & 0.805A for the Ha spectra for 09Jan19, 12Dec19, & 13Jan20 respectively.
It still looks like Betelgeuse EW at Ha has decreased significantly since last year.

James

Hi James and others,

I transfered James' last post in Software/Spcaudace section:
http://www.spectro-aras.com/forum/viewt ... 757#p13757

EW measurement will follow there.

Benji