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Chandra X-ray Center (CXC)
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The Great Observatory quartet of missions -- Hubble Space Telescope
(launched 1990) Compton Gamma-ray Observatory (1991) Chandra X-ray
Observatory (1999) Spitzer Space Telescope (2003) -- had a major
impact on astronomy.  Chandra built on the success of Einstein
(grazing incidence) and was both an imaging and spectroscopic
mission. It remains the highest angular resolution mission at X-ray
bands with no successor in sight (in this regard).

Programs:
$ csChandra .. cone search
$ wsCXO ... weekly status of the Chandra X-ray Observatory

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Simple cone search
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CXC provides a convenient command line interface (CLI) to the holdings
of the Chandra data base
	https://cxc.cfa.harvard.edu/csc/cli/index.html


This is, by far the simplest and most useful, query and, like all
respectable data archives, CXC hosts this tool.  The base URL is
	http://cda.cfa.harvard.edu/csc2scs/coneSearch
and an example is

$ curl "http://cda.cfa.harvard.edu/csc2scs/coneSearch?RA=$RA&DEC=$DEC&SR=$SR&VERB=2" -o out.vot
where $RA, $DEC, SR are in decimal degrees and VERB=1,[2],3 (see
Appendix I) and the ouput is a VO table.

I have written a Unix wrapper to this call and also a decoder to
convert the VO Table to a csv file. My program also, on request,
produces, a header file.

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Weekly status of Chandra X-ray Observatory
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Curious to know what CXO has been doing for this week?

$ wsCXO


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Appendix I: Cone Search
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REFERENCE: http://cda.cfa.harvard.edu/cscvo/


RA - Right Ascension in decimal degrees
DEC - Declination in decimal degrees
SR - Search Radius in decimal degrees
VERB -Verbosity of the result set. Defaults to 2. The following
      values are allowed: verbosity = 1 reports the source name,
      ra and dec values from the master source table for each
      matching source resulting from the cone search - verbosity =
      2 reports the master source summary results (the default
      verbosity level) - verbosity = 3 reports all the columns in
      the master source table
1 - Reports the source name, ra and dec values from the master
    source table for each matching source resulting from the cone
    search
2 - Reports the following properties from the master source table:
    m.name, m.ra, m.dec, m.err_ellipse_r0, m.conf_flag, m.sat_src_flag,
    m.significance, m.flux_aper_b, m.flux_aper_lolim_b,
    m.flux_aper_hilim_b, m.flux_aper_w, m.flux_aper_lolim_w,
    m.flux_aper_hilim_w, m.extent_flag, m.hard_hm, m.hard_hm_lolim,
    m.hard_hm_hilim, m.hard_ms, m.hard_ms_lolim, m.hard_ms_hilim,
    m.var_intra_index_b, m.var_inter_index_b, m.var_intra_index_w,
    and m.var_inter_index_w
3 - Reports all master source properties

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VOTable
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