CCD Observing VSS Workshop Hampshire Astronomical Group 13 th March 2010 Roger Pickard, Director BAA VSS

CCD Observing The introduction of CCDs to the amateur market has also revolutionised the way some observers undertake their observations. VSS has introduced a CCD target list of variable stars suitable for different levels of interest, equipment and observer skills.

CCD Observing

DV UMa CCD Observing

But how do you obtain data like that? Firstly, of course, you must decide what to observe! Ideally, an object that is going to “do” something. We list some easy objects on the web site. In addition, you may wish to subscribe to the BAA VSS Alert notices. Whatever, obtaining the images is only the first stage CCD Observing

So, you have some images, but how do you get from - CCD Observing To -

One example is to use AIP4WIN The VS Section has developed an Excel program that takes the output from AIP4WIN and does all the hard work for you CCD Observing

AIP4WIN in use Flats and darks CCD Observing

AIP4WIN in use Flats and darks CCD Observing

AIP4WIN in use CCD Observing Don’t forget to tick “Auto-Calibrate”

CCD Observing For CCD users it’s probably best to use The AAVSO charts from:- Display (or print) the appropriate chart

CCD Observing You can also obtained accurate photometry for the comparison stars. This allows you to set various parameters to suit your own telescope.

AIP4WIN in use CCD Observing The chart and photometry

AIP4WIN in use CCD Observing

AIP4WIN in use – A small part of the output file AIP4Win Multiple-Image Photometry Tool Ensemble Photometry Report AIP4Win Licensed to: Roger Pickard AIP4Win v Folder containing files: C:\~Imaging\2010\02\11\ER UMa Filename of first image: IMG6156.FIT Number of files selected: 175 Star aperture radius: 8 Sky annulus inner radius: 10 Sky annulus outer radius: 14 Star aperture pixels: 202 Sky annulus pixels: 182 Default integration time: 60.0 Zero point: 25.0 Gain [e/ADU]: 1.0 Readout noise [e rms]: 10.0 Dark current [e/sec/pix]: 1.0 Time of observation: Date, time, exposure from FITS header CCD Observing

The VSS Excel spreadsheet – opening page CCD Observing

The VSS Excel file – Results page CCD Observing

The VSS Excel file – Data Charts page CCD Observing

Filters! CCDs allows much smaller magnitude variations to be detected than by NE If you use Photometric filters CCDs also allows much more information to be obtained from your data. CCD Observing

A Photometric system is a set of well-defined passbands. The first known standardized photometric system is the Johnson- Morgan or UBV photometric system (1953). At present, there are more than 200 photometric systems!UBV photometric system Photometric systems are usually characterized according to the widths of their passbands: broadband (passbands wider than 30 nm (the most widely used is Johnson-Morgan UBV system)),UBV system intermediate band (passbands widths between 10 and 30 nm), narrow band (passbands widths less than 10 nm). Photometric systems CCD Observing

Colour response and Johnson-Morgan UBV system CCD Observing

Some well known stars CCD Observing

Color Indices Color index is defined by taking the difference in magnitudes at two different wavelengths. Using the U, B, V colour filters, there are three independent possible such differences. The B-V colour index is defined by taking the difference between the magnitudes in the blue and visual regions of the spectrum; The U-B colour index is that between the ultra-violet and blue regions. CCD Observing

Color Index Examples Spica has apparent magnitudes U = -0.24, B = 0.7, and V = 0.9 The corresponding color indices are:- B - V = = U - B = = Generally, negative values indicate that a star is hot (most radiation coming at shorter wavelengths). Antares B = 2.7 and V=0.9, and the B - V color index is B - V = = 1.8 The positive value of B - V in this case is an indication that Antares is a cool star, with most of its radiation coming at longer wavelengths. CCD Observing

Table of example B - V and U - B mags StarTypeB-VU-B Y CVnN  Cep M  Ori (Betelgeuse) M  Tau (Aldebaran) K 1 Cen G  CMi (Procyon) F Eri BDA  CMa (Sirius) A  Eri (Achernar) B  Pup O CCD Observing

Note: Unfiltered CCDs are usually red sensitive and so see red stars much brighter that visual observers do. CCD Observing

Basic CCD Data – observe once per night reporting any changes StarRA (2000)Dec (2000)TypeRange V452 Cas UGSU GO Com UGSU V KV Dra UGSU V V478 Her UGSU p DV Dra UGSU/UGWZ15.0-<21p HR Lyr N (or NR) v V1363 Cyg ?13.0-<17.6p V1316 Cyg UGSU14.5 – 17.8C TY Vul UG p V630 Cas UG p CCD Observing

Time resolved photometry – observe one star all night long, if possible. StarRA (2000)Dec (2000)TypeRange SV CMi UGZ V ES Dra UGSU? p HR Lyr N (or NR) v CG Dra UG p V1363 Cyg ?13.0-<17.6p CCD Observing

Easy – instant results (well, a couple of hours) StarRA Dec TypeMaxMinMinOrbitalCompComp IIIPeriodV magGSC AD And EB d OO Aql EW d AC Boo EW d EG Cep EB d TZ Lyr EB d ER Ori EW d CCD Observing

SUMMARY CCD observations are easy to make. Reducing the observations is made easier by the use of the VSS Excel spreadsheet. Filtered observations are something to work up to – if you wish. Professionals need your observations Thank You