[John Coffin]

Here is the text of the ISIS report after pressing the Go button on the calibration assistant.

Extract spectral profile… 

Input image : c:spectra20181028mean.fit

Y-coordinate of binning zone : 532

Binning zone width : 27

Sauve the rectified image : c:spectra20181028@.fit

Save the profile : c:spectra20181028@.dat  (uncalibrated spectra)

Ok. 

——————————————

Extract spectral profile… 

Input image : c:spectra20181028neon5.fit

Y-coordinate of binning zone : 532

Binning zone width : 27

Sauve the rectified image : c:spectra20181028@@.fit

Save the profile : c:spectra20181028@@@@.dat  (uncalibrated spectra)

Ok. 

————————————————————————–

Lines search zone  

|  -5  |  373  |  3  |

|  -5  |  384  |  3  |

|  -5  |  401  |  3  |

|  -4  |  428  |  4  |

|  -5  |  478  |  3  |

|  -3  |  584  |  5  |

|  -5  |  790  |  7  |

|  -5  |  809  |  7  |

|  -6  |  878  |  6  |

|  -5  |  929  |  7  |

|  -6  |  1070  |  6  |

|  -8  |  1124  |  6  |

|  -10  |  1202  |  4  |

Gaussian fit on : +/-5 pixels  

————————————————————————–

Reciprocical inverse dispersion equation  

Coefficient a4 : 2.039047E-10

Coefficient a3 : -1.032328E-06

Coefficient a2 : 1.289598E-03

Coefficient a1 : 4.25183

Coefficient a0 : 2113.351

————————————————————————–

Fitting deviation (wavelength)

point #1  x = 373.309  lambda = 3835.394  dlambda = -0.004

point #2  x = 384.441  lambda = 3889.156  dlambda = -0.106

point #3  x = 401.092  lambda = 3969.698  dlambda = 0.382

point #4  x = 428.333  lambda = 4101.743  dlambda = 0.007

point #5  x = 477.589  lambda = 4341.144  dlambda = -0.664

point #6  x = 584.329  lambda = 4860.809  dlambda = 0.531

point #7  x = 790.079  lambda = 5852.713  dlambda = -0.223

point #8  x = 809.454  lambda = 5944.744  dlambda = 0.086

point #9  x = 877.733  lambda = 6266.474  dlambda = 0.016

point #10  x = 929.332  lambda = 6506.631  dlambda = -0.101

point #11  x = 1070.153  lambda = 7147.050  dlambda = -0.010

point #12  x = 1123.593  lambda = 7383.774  dlambda = 0.176

point #13  x = 1201.871  lambda = 7723.850  dlambda = -0.090

————————————————————————–

RMS : 0.351305 (in angstroms)

————————————————————————–

Ok.

Here is the report from the Go page.

Load the image : c:spectra20181028zeta_draconis-1.fit

Load the image : c:spectra20181028zeta_draconis-2.fit

Load the image : c:spectra20181028zeta_draconis-3.fit

Load the image : c:spectra20181028zeta_draconis-4.fit

Load the image : c:spectra20181028zeta_draconis-5.fit

Load the image : c:spectra20181028zeta_draconis-6.fit

Substract the offset : c:spectra20181028caliboffset.fit

Substract the dark : c:spectra20181028calibdark600_b2_minus10-.fit

Dark coefficient (1) : 0.0333

Dark coefficient (2) : 0.0333

Dark coefficient (3) : 0.0333

Dark coefficient (4) : 0.0333

Dark coefficient (5) : 0.0333

Dark coefficient (6) : 0.0333

Divide by the flat-field : c:spectra20181028flat.fit

Flat-field level : 38002

Cosmetic correction : c:spectra20181028calibcosme.lst

Smile correction – Y0 = 658  Radius = 11056

Transverse registration at intermediate Y coordinate = 532.00

Spectrum Y coordinate Y 1 = 533.31

Spectrum Y coordinate Y 2 = 533.47

Spectrum Y coordinate Y 3 = 533.53

Spectrum Y coordinate Y 4 = 533.73

Spectrum Y coordinate Y 5 = 533.76

Spectrum Y coordinate Y 6 = 533.58

Remove sky background

Save image : c:spectra20181028@s.fit (sky not removed)

Save 0b product : c:spectra20181028_Zeta Dra.fit (2D image)

Adopted Y coordinate : 531.51

Tilt correction (second pass)

Remove sky background (second pass)

Write 2D image : c:spectra20181028@1.fit

Write 2D image : c:spectra20181028@2.fit

Write 2D image : c:spectra20181028@3.fit

Write 2D image : c:spectra20181028@4.fit

Write 2D image : c:spectra20181028@5.fit

Write 2D image : c:spectra20181028@6.fit

Optimal binning

Write raw profile : c:spectra20181028@raw1.dat

Write raw profile : c:spectra20181028@raw2.dat

Write raw profile : c:spectra20181028@raw3.dat

Write raw profile : c:spectra20181028@raw4.dat

Write raw profile : c:spectra20181028@raw5.dat

Write raw profile : c:spectra20181028@raw6.dat

Intensity of individual profiles (ADU)…

Mean (median) for profile #1 : 277922 (48733)

Mean (median) for profile #2 : 267284 (46730)

Mean (median) for profile #3 : 274253 (46119)

Mean (median) for profile #4 : 283042 (47260)

Mean (median) for profile #5 : 261331 (48022)

Mean (median) for profile #6 : 247607 (44406)

Standard summation of individual profiles

Save uncalibrated spectral profile : c:spectra20181028@star.dat

Processing of calibration image : c:spectra20181028neon5.fit

Dark coefficient (calibration) : 0.0083

Save image : c:spectra20181028@calib.fit (2D image)

Save spectral profile : c:spectra20181028@calib.dat

Spectral calibration

Computed A0 parameter : 2113.160 (actual polynom A0 = 2113.351)

Predefined dispersion polynom :

Coefficient a4 : 2.039047E-10

Coefficient a3 : -1.032328E-06

Coefficient a2 : 1.289598E-03

Coefficient a1 : 4.25183

Coefficient a0 : 2113.351

—————————————————————————-

Normalization spectral range : [6650  –  6750]

Normalization value (final profile) : 42238320.9

Normalization value (individulal profile #1) : 7339427.7

Normalization value (individulal profile #2) : 7005366.1

Normalization value (individulal profile #3) : 7012000.4

Normalization value (individulal profile #4) : 7058567.1

Normalization value (individulal profile #5) : 7157459.9

Normalization value (individulal profile #6) : 6665499.8

—————————————————————————-

Spectrum #1   ( b ) – ( v ) intensity = ( 0.839 ) – ( 0.996 )

Spectrum #2   ( b ) – ( v ) intensity = ( 0.862 ) – ( 0.994 )

Spectrum #3   ( b ) – ( v ) intensity = ( 0.913 ) – ( 0.997 )

Spectrum #4   ( b ) – ( v ) intensity = ( 0.951 ) – ( 0.998 )

Spectrum #5   ( b ) – ( v ) intensity = ( 0.786 ) – ( 0.996 )

Spectrum #6   ( b ) – ( v ) intensity = ( 0.798 ) – ( 0.997 )

( b ) – ( v ) mean intensity = ( 0.858 ) – ( 0.996 )

( b ) – ( v ) median intensity = ( 0.862 ) – ( 0.997 )

—————————————————————————-

Write individual DAT processed profile : c:spectra20181028@pro1.dat

Write individual DAT processed profile : c:spectra20181028@pro2.dat

Write individual DAT processed profile : c:spectra20181028@pro3.dat

Write individual DAT processed profile : c:spectra20181028@pro4.dat

Write individual DAT processed profile : c:spectra20181028@pro5.dat

Write individual DAT processed profile : c:spectra20181028@pro6.dat

Write individual FITS processed profile : c:spectra20181028@pro1.fit

Write individual FITS processed profile : c:spectra20181028@pro2.fit

Write individual FITS processed profile : c:spectra20181028@pro3.fit

Write individual FITS processed profile : c:spectra20181028@pro4.fit

Write individual FITS processed profile : c:spectra20181028@pro5.fit

Write individual FITS processed profile : c:spectra20181028@pro6.fit

—————————————————————————-

Write final profile : c:spectra20181028_zetadra_20181028_970_J_Coffin.fit

Write final profile : c:spectra20181028_zetadra_20181028_970_J_Coffin.dat

Intermediate files removed

—————————————————————————-

Acquisition starting date : 28/10/2018 23:16:27

Duration : 42.0 secondes

Mid-exposure date : 28.970/10/2018

Mid-exposure Julian day : 2458420.4700

Resolution power : 521.5

Ok. 

[John Coffin]

Thanks for your helpful advice. The  chart relating error to altitude was very useful Robin. For other readers this is the final link to it.

http://www.astronomie-amateur.fr/Documents%20Spectro/Ref_013.pdf

I must try and find my targets before they get too low in the sky!

[John Coffin]

I would be interested in tackling some test targets. More help with ISIS would be useful and also the advanced processing too. I can get ISIS to work but I nearly always hit a problem that takes a lot of effort to overcome. 

[John Coffin]

Dear Robin, your method worked. Thanks a lot. The calibration is shifted to the blue by about 1.5 A, so I guess the lesson to learn here is for me to get my spectrum straight and try again. Here are my first spectra with this set up. 

[John Coffin]

i was surprised that ISIS doesn’t recalculate the X position if the spectrum is rotated. I knew the spectrum was not horizontal, it was my first one with the new camera, but assumed that when ISIS measured the tilt it would make the necessary corrections. Thanks again, I am babysitting today but will try your sugestions tomorrow.

[John Coffin]

Dear Robin, I hope you were up observing and not just working on my problem. I am most grateful for your help and will follow your advice.

Many thanks, John

[John Coffin]

Thanks, am emailing you two zip files now. John

[John Coffin]

Dear Robin, I tried checking that the smile correction is working but unfortunately I couldn’t get a result. I am obviously not doing it properly. I will look at your lamp image.

[John Coffin]

i calibrated the same star in RSpec using a third order polynomial and with an RMS of 0.6539, just by using the Balmer lines. I’d really rather be able to use ISIS as it is so much more powerful and does all the stacking etc. 

[John Coffin]

Thanks for your suggestion. The best calibration I can get with the method you suggested gives an RMS of 19.976 Angstroms. I hope I am using the correct neon line (marked below with an arrow). I have even updated the version of ISIS to the latest one. I have also tried adjusting the pixel scale by increments of 0.02, but no luck. 

[John Coffin]

Forgive me, I’m new to the BAA. I will do as Andy suggests. John.

[John Coffin]

I didn’t notice this request  for spectroscopic monitiring of this object in the spectroscopy section.

[John Coffin]

Thank you both for your very helpful comments and for the trouble you have taken to produce  your data. I will experiment to see how much I can cool the camera.  I didn’t realise that ‘warm pixels‘ can still collect useful information  and that is reassuring.   

[John Coffin]

Thanks, that makes sense. The DSLR will probably need changing for a CCD when I tackle fainter targets and funds become available. John. 

[John Coffin]

Why are there emission lines for Fe but not C, N, and O which must be present in the star before iron can be formed? If the iron is dredged up from the star’s core wouldn’t C, N and O be dredged up too? The ionisation potential for Fe is similar to the other metals. Surely it can’t be just centrifugal force that brings the Fe to the surface and into the circum-stellar disc in preference to the lighter elements? 

[John Coffin]

Thanks. I should have looked at Walker’s atlas. I have the PDF version. 

[John Coffin]

Thanks everyone for all your help. Here is the final calibrated spectrum of Merak captured with a full spectrum modified Canon 450D and an Alpy. I was using a 500 mm focal length refractor and used a QHYCCD Polemaster as an electronic finder. It has a huge field of view (11 x 8 deg) but showed stars down to magnitude 8 surprisingly. 

[John Coffin]

Thanks Robin, that’s really useful advice. I do have the Alpy barlow. I changed the pixel size as you suggested and it worked. RMS now 0.12. John

[John Coffin]

Thanks for the above advice. I’ve also installed Starlight Live to use with a Lodestar to make a sensitive electronic finder. 

[John Coffin]

i took Alun’s advice and bought the secondhand Lodestar. The QHY5 is now attached to the finder and the Lodestar to the guide module on the Alpy.

I lined them up on a radio mast a mile away.

Here’s a write up. All I need is a clear night!

John

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