john simpson

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  • in reply to: Relative Flux Calibration #577876
    john simpson
    Participant

    Thanks for the quick response Andrew – yes, not the same, but similar air mass. The two in the graph are close together and image sequences were taken one after the other over 25mins or so. Altitude range 51-52 deg. I’m ALPY novice so I suspect something basically wrong about my set-up or what I’ve done to process, the errors seem to be too big compared to what’s been achieved by Robin. The annoying thing is that the corrected HD27819 seemed so close to its Miles library ref.

    john s

    in reply to: Help with ISIS #577809
    john simpson
    Participant

    Hi David/Robin,

    I am wondering if my interpretation of RMS performance index reported for dlambda is incorrect in this instance? It appears to be sqrt of sum of squares/3.  [3 being order of polynomial -1].

    john

    in reply to: Help with ISIS #577798
    john simpson
    Participant

    Robin et al,

    Thought I’d better make it clear that in my original post with the coefficients, I put in copy the lower set that is reported in the log file.  .  There is an upper set reported call the “primary dispersion” which I couldn’t relate to my pixel data, but guessed it was some master set in ISIS covering 11 different wavelengths, amended by my data in some way to allow setting of the research pixel windows of +/-7. I’m copying this set below anyway, just in case it’s relevant.

    ————————————————————————–

    Primary dispersion :

    Coefficient a4 : -2.657745E-13

    Coefficient a3 : 7.117650E-09

    Coefficient a2 : -6.547758E-05

    Coefficient a1 : 0.53625

    Coefficient a0 : -971.891

    ————————————————————————–

    RMS : 0.125248 (en pixels)

    ————————————————————————–

    Primary wavelength fit deviation

    point #1  Lambda = 3770.630  px = 447.009  dx = -0.091

    point #2  Lambda = 3797.300  px = 454.713  dx = 0.211

    point #3  Lambda = 3835.390  px = 465.697  dx = -0.107

    point #4  Lambda = 3889.050  px = 481.138  dx = -0.018

    point #5  Lambda = 3970.080  px = 504.383  dx = 0.059

    point #6  Lambda = 4101.750  px = 541.995  dx = -0.068

    point #7  Lambda = 4340.480  px = 609.798  dx = -0.023

    point #8  Lambda = 4861.340  px = 756.864  dx = 0.054

    point #9  Lambda = 6562.850  px = 1246.125  dx = -0.096

    point #10  Lambda = 6869.000  px = 1337.306  dx = 0.092

    point #11  Lambda = 7605.000  px = 1560.933  dx = -0.012

    ————————————————————————–

    BTW, if I calculate the RMS for the dx above I get 0.09241 and not 0.125248 [maybe it is weighted in some way not disclosed]. The same is true for the dlambda figures noted in my earlier post.

    john

    in reply to: Help with ISIS #577795
    john simpson
    Participant

    Hi Robin, thanks for looking into this – I’ll do as you suggest and calibrate with Balmer line option for the time being.

    john

    in reply to: Help with ISIS #577791
    john simpson
    Participant

    Hi Andy, Thanks for your quick reply. Yes, hovering over spectrum plot in tab 5 seems OK – very noisy, 4 images done in hurry with poor guiding, but think OK. Too excited with ALPY. Will attach plot. Used HD27819 – Miles – A7v – had aimed to try to follow Robin’s earlier set that he posted, but ran out of weather. Used “Predefined Mode” ALPY 600 (Balmer Lines) in Spectral Box of General tab.  This is what appears in log file.

    Wavelength fit deviation
    point #1  x = 303.320  lambda = 3834.846  dlambda = 0.544
    point #2  x = 318.889  lambda = 3889.410  dlambda = -0.360
    point #3  x = 342.002  lambda = 3970.510  dlambda = -0.430
    point #4  x = 379.334  lambda = 4101.764  dlambda = -0.014
    point #5  x = 446.859  lambda = 4340.099  dlambda = 0.381
    point #6  x = 593.448  lambda = 4861.471  dlambda = -0.131
    point #7  x = 1081.158  lambda = 6562.787  dlambda = 0.023
    point #8  x = 1179.852  lambda = 6872.013  dlambda = -0.013
    ————————————————————————–
    Coefficient a4 : -4.314777E-10
    Coefficient a3 : 7.466854E-07
    Coefficient a2 : -3.481507E-04
    Coefficient a1 : 3.55629
    Coefficient a0 : 2767.495
    ————————————————————————–
    RMS : 0.507955
    ————————————————————————–

    Don’t have ALPY Calibration Module – need coffers to refill for that. Have fashioned external fixed neon bulb in line with slit as per picture on Robin’s website, but didn’t use that – took some sky plus neon today though to play with later.

    Am going to do it all over again next clear spell here, but will keep looking at it – still puzzled.

    in reply to: ALPY TITAN #577781
    john simpson
    Participant

    Nick,

    Think this is the problem I encountered [Santa forgot!]. You need this spacer from Shelyak [or elsewhere]

    M42 (m) – C (f) spacer – BA0034.

    Regards

    in reply to: Aha… Not quite as expected! #577729
    john simpson
    Participant

    Not sure if this helps or not, maybe just typo but your chart shows HD222368 [which is Miles listed in ISIS], but 132 Tau is HD 38751[also Miles listed] and quite some distance away?

    Regards

    john s

    in reply to: Wolf Rayets and Symbiotics spectra – a busy night! #577062
    john simpson
    Participant

    Hi Andy,

    Yes – happy for you to use whatever you want.  My reason for earlier question about normalisation of spectra was that I took sets of images in between the dates given in the figure.  Haven’t processed all of them yet, but had it in mind to see if I could put some numbers to any changes by measuring equivalent widths if possible [Richard Walker document explains how to do this and Rspec has facility to do the measurements – not sure how accurate though – would be first try out of it].

    Cheers

    john s

    in reply to: Wolf Rayets and Symbiotics spectra – a busy night! #577057
    john simpson
    Participant

    Hi Steve, Andy,

    Thought I’d add one more to your impressive collection – as well as AG Pegasi & Chi Cygni I chose to follow CH Cygni. Even at low resolution CH Cygni is a real gem for a beginner to follow and try to understand – changes in the spectrum abound – this plot shows changes to H and He lines in just a month [He disappear!]. I used iota CYG as reference. Wondered if you could give some tips on how to normalise in situations like this when continuum so broken up?

    Cheers

    john s

    in reply to: Symbiotic ag Peg! #576999
    john simpson
    Participant

    Hi Steve,

    Yes, think our posts did cross. I agree too with your logic, would be best if all observers could use same reference, whatever it was agreed to be. Since still experimenting have made note to do comparison based on several references at next available opportunity to see what differences accrue. My efforts for AG Pegasi on 16th Aug. attached. A lot of noise, but H alpha, beta, gamma clear – also some He I & II lines.

    in reply to: Symbiotic ag Peg! #576996
    john simpson
    Participant

    Hello Andy, Steve,

    Thanks to both of you for posting your spectra – they are impressive and in my case certainly of great help because I can compare with my own low resolution spectra using SA200 & DSLR.  I have been following Chi Cygni & AG Pegasi [and also CH Cygni] since July/Aug, at low reolution and at other end of learning curve to you.  I have used several different references to correct for for instrument and atmospheric extinction effects, but am wondering if I should be using some recognised standard stars that are in common use – depending on target RA/DECL? So far I’ve tried to find a nearby A class star of roughly the same magnitude to use, but is there somewhere a preferred/recommended list?

    Best Wishes

    john s

    in reply to: chi Cygni 2015 #576975
    john simpson
    Participant

    Andy,

    Thanks for posting your spectral profile of Chi Cyg. RSpec and an SA200 recent purchases for me, still experimenting with set-up and working through the tutorials, but couldn’t resist having a look after Gary’s first post. Confidence booster to see similarities in the profiles even though mine just a single 20 sec. image with C6/collimator/SA200/DSLR wavelength calibrated only. Thanks.

    john s

Viewing 12 posts - 21 through 32 (of 32 total)