Radiation astronomy/First X-ray source in Antlia

The first X-ray source in Antlia is unknown.

Inside the white circle is a new supernova remnant in Antlia. Credit: P. R. McCullough, Brian D. Fields, and Vasiliki Pavlidou.

This is a lesson in map reading, coordinate matching, and researching. It is also a research project in the history of X-ray astronomy looking for the first astronomical X-ray source discovered in the constellation of Antlia.

Nearly all the background you need to participate and learn by doing you've probably already been introduced to at a secondary educational level.

Some of the material and information you'll be introduced to is at the college or university level, and as you progress in finding X-ray sources, you'll run into concepts and experimental tests that are actual research.

To succeed in finding an X-ray source in Antlia is the first step. Next, you'll need to determine the time stamp of its discovery and compare it with any that have already been found. Over the history of X-ray astronomy a number of sources have been found, many as point sources in the night sky. These points are located on the celestial sphere using coordinate systems. Familiarity with these is not a prerequisite. Here the challenge is geometrical, astrophysical, and historical.


Def. a natural source usually of radiation in the sky especially at night is called an astronomical source.

Many X-ray sources do not remain in a constellation for lengthy periods. Some of these are the Sun and sources apparently in orbit around the Sun. The Sun travels through the 13 constellations along the ecliptic, the 12 of the Zodiac and the constellation Ophiuchus.


To introduce yourself to some aspects of the challenge may I suggest reading the highlighted links mentioned above, and if you're curious, those listed under the section See also below.

X-rays are a form of radiation that is currently part of the electromagnetic radiation intersecting the Earth. More information about radiation is in radiation astronomy.

First astronomical sourceEdit

In the context of radiation astronomy, the first astronomical source may not have been from the sky.

Hominins are intelligent life forms on Earth. It may be true that hominins seldom pay attention to those things that seldom affect them in a harmful way, or that are not edible, do not provide or are not useful for shelter, or have little positive effect on health and well-being.

On the other hand, hominin curiosity may make everything something to pay attention to.

First astronomical X-ray sourceEdit

Astronomical X-ray sources surround the Earth from above. These natural X-ray sources irradiate the Earth, but the atmosphere absorbs the X-rays before they reach the surface.

A first astronomical X-ray source is usually considered to be the Sun.

Def. a natural source usually of radiation in the sky especially at night is called an astronomical source.

X-ray astronomy uses a variety of X-ray detectors often fashioned into X-ray telescopes to detect and observe natural sources that emit, reflect, or fluoresce X-rays.

Def. a natural source usually of X-rays (X-radiation) in the sky especially at night is called an astronomical X-ray source.

X-ray emission occurs from many celestial objects. These emissions can have a pattern, occur intermittently, or as a transient astronomical event. Often, the first X-ray source discovered in many constellations is an X-ray transient. These objects show changing levels of X-ray emission. There are a growing number of recurrent X-ray transients.

"[T]he sky is known to be full of transient objects emitting at X- and gamma-ray wavelengths"[1].

Searching for the first sourceEdit

Searching for the first X-ray source per constellation, or such a search, is an historical activity that begins in the 1960s as original research that first requires determining the exact boundaries of each constellation.

There are 88 modern constellations that the International Astronomical Union (IAU) has used to divide the celestial sphere into 89 irregularly shaped boxes. The constellation Serpens is split into two separate sections, Serpens Caput (the snake's head) to the west and Serpens Cauda (the snake's tail) to the east.

Many X-ray sources do not belong to a constellation. Some of these are the Sun and sources apparently in orbit around the Sun. The Sun travels through the 13 constellations along the ecliptic, the 12 of the Zodiac and the constellation Ophiuchus.


This is an image of the International Astronomical Union (IAU) sky map of the constellation Antlia. Credit: IAU and Roger Sinnott & Rick Fienberg, Sky & Telescope magazine.

The Wikipedia article about the constellation Antlia contains a high school level description. The figure at right shows the sky map of Antlia. Around the edges of the map are coordinates related to longitude and latitude, but with the Earth rotating on its axis every 24 hours the celestial coordinates must remain fixed. How has this been accomplished?

The Sun is an X-ray source that travels through the 13 constellations along the ecliptic. Is Antlia a constellation that the Sun travels through?

Also, in the Wikipedia article is a list of stars in Antlia. What's the difference between a star and an astronomical X-ray source?

Occasionally an X-ray source is found with coordinates close to the boundaries of Antlia. Using the coordinates from the Wikipedia article on Epsilon Antliae for this star, a search on NED under 'External links' indicates an X-ray source near the star: "1RXS J092856.0-354610". Test this yourself by clicking on the NASA NED link below. Click on the 'Near position' search. Enter the coordinates for Epsilon Antliae into the longitude block as "09 29 14.7", without the quotes. And, the latitude block as "-35 57 05", without the quotes. Try a radius of 20.0 arcmin, and click on 'search'.

Boundary coordinates from the IAU for Antlia
Right ascension in hours (h) minutes (m) seconds (s) Declination in degrees
09 27 37.0404 -24.5425186
09 27 05.1837 -37.2920151
09 26 56.1747 -40.2918739
11 05 49.5611 -40.4246216
11 05 55.0471 -35.6746559
10 55 50.0437 -35.6664963
10 55 54.6924 -31.8332005
10 40 48.3309 -31.8185863
10 40 51.0945 -29.8186131
10 20 43.5185 -29.7947845
10 20 47.8410 -27.1281624
09 50 38.2279 -27.0835037
09 50 43.1235 -24.5835705

Try locating approximately each of the coordinates from the table above for inflection points (changes of arc) that are the current boundary for Antlia on the map.

Is the NED X-ray source within Antlia?

Searching for a source in SIMBADEdit

In the Wikipedia article on the constellation Antlia are a number of key words or abbreviations that can be used to search the SIMBAD database. For example, "NGC 2997, a spiral galaxy, and the Antlia Dwarf Galaxy lie within Antlia's borders. Clicking on the image for NGC 2997 brings up "File:NGC 2997 ESO.jpg.

Another way to find possible X-ray sources in Antlia is to use other search queries on SIMBAD.

Click on the SIMBAD link under "External links" below, then click on "Criteria query".

In the tan box, type in " cat='NGC' & otype='X' " without the quotes and the spaces after and before these quote marks. This tells the SIMBAD computer you are interested in searching the catalog NGC for X-ray source type objects.

Over at the right from the tan colored box: "Return", the default is "object count". Click on "submit query". In a few moments a result something like "Number of objects: 1387" should appear. Click "Back" to see the tan box again and change "object count" to "display".

SIMBAD will list all these objects with appropriate coordinates that you may compare with the coordinates for Antlia to determine which of these X-ray source objects are in Antlia. I found NGC 3258, NGC 3271, and NGC 3281. Which ones did you find? Other object types that can be searched are 'Sy1' and 'Sy2' combined with otype='X' yield a few more X-ray sources.

Searching for a source on WikipediaEdit

An easy way to find possible X-ray sources in Antlia is to search Wikipedia using "Antlia" without the quotes and "X-ray" with the quotes. The Antlia Cluster and Delta Antliae are returned, for example.

Testing a sourceEdit

There are many web sites that may have an X-ray source listed for the constellation Antlia.

Wikipedia sourcesEdit

Under "Notable features" in the Wikipedia article on the constellation Antlia is the brightest star: Alpha Antliae. In the star box of the Wikipedia article alpha Antliae, below the image of the star are coordinates:

  1. Right ascension: 10h 27m 09.1011s and
  2. Declination: -31° 04' 04.004".

Find these coordinates on the Antlia map at the right. Is alpha Antliae really inside the boundaries of the constellation?

To evaluate the star as an X-ray source, skip ahead to section "X-ray source".

Another way to find sources is to search Wikipedia using "Antlia" and "X-ray".

SIMBAD sourcesEdit

Another way to find possible X-ray sources in Antlia is to use other search queries on SIMBAD.

Click on the SIMBAD link under "External links" below, then click on "Criteria query".

In the tan box, type in "region(10 27 09.1011 -31 04 04.004, 10m)", without the quotes. This tells the SIMBAD computer you are interested in a circular region of the celestial sphere centered on the coordinates for alpha Antliae, with a radius of 10 arcminutes (m).

Notice on the page over at the right from the tan colored box: "Return". The default is "object count". Click on "submit query". In a few moments a result something like "Number of objects: 7" should appear. Click "Back" to see the tan box again.

Add "otype='X'" to the entry so that it reads: "region(10 27 09.1011 -31 04 04.004, 10m) & otype='X'", without the outside quotes. Click on "submit query" again. If the result is "0" number of objects, increase the number of arcminutes, or use "1d" which stands for "one degree".

When you find at least one object, change "Return" to "display" by clicking on the circle to its left, then "submit query".

X-ray sourcesEdit

There are several ways to evaluate an X-ray source for the constellation Antlia.

A Wikipedia sourceEdit

In the Wikipedia article on Alpha Antliae, use the 'find' command of your browser to see if this Wikipedia page mentions anything about "X-ray", or "X-rays". Does the article mention whether or not Alpha Antliae is an X-ray source?

What is the current time stamp for the Wikipedia article on Alpha Antliae?

From reading the Wikipedia article on Alpha Antliae, if you believe the text demonstrates that Alpha Antliae is not an X-ray source in Antlia edit the "Non-X-ray source in Antlia" section near the bottom of the page with an entry similar to "# Alpha Antliae 4 October 2011 at 22:45 Wikipedia article "Alpha Antliae".", without the outer quotes, and finish the entry with four "~"s without the quotes. The date included with your designation or username is a time stamp for the entry. In the entry itself "4 October 2011 at 22:45" is a time stamp from the Wikipedia article on Alpha Antliae shown at the bottom of the page. The last portion of the entry is the source of your information.

Is Wikipedia a 'primary source'?

Even though Wikipedia has an article on Alpha Antliae, is it a good place to stop in testing whether Alpha Antliae has been detected as an astronomical X-ray source?

A SIMBAD sourceEdit

Provided under 'External links' at the bottom of this page are a number of helpful links. If your browser allows you to view a second window in parallel with this one, click on the external link to the "SIMBAD Astronomical Database".

At the lower right side of the SIMBAD Astronomical Database page is a "Basic search" box. There are several ways to try your target:

  1. source name: without the quotes use "alpha Antliae", "alpha antliae", or "Alpha Antliae" or
  2. source coordinates: without the quotes "10 27 09.1011 -31 04 04.004".

The names take you directly to "* alf Ant", but the coordinates yield a list, what's the difference between "* alf Ant" in the table and "Alpha Antliae" on Wikipedia?

If you are looking at the table which lists possible targets, click on the entry "* alf Ant" to look at the entry.

On the page "* alf Ant" read down the left side until you see "Other object types:". To the right of this is a list of other object types that Alpha Antliae is. Look for an X. Is there one in this horizontal list?

SIMBAD time stampEdit

Peruse the SIMBAD page for a time stamp or date of last revision.

If the entry at SIMBAD convinces you that Alpha Antliae is not an X-ray source, edit the "Non-X-ray source in Antlia" section near the bottom of this page and type in an entry similar to "# Alpha Antliae 2012.01.07CET19:20:27 SIMBAD article "* alf Ant".", without the first set of quotes, followed by four ~s.

Challenging an entryEdit

Is SIMBAD a 'primary source'?

SIMBAD is an astronomical database provided by the Centre de Données astronomiques de Strasbourg. It is an authoritative source, but they do occasionally make a mistake.

If you find an X-ray source within the constellation on SIMBAD, the next step is to find the earliest time stamp of discovery.

Primary sourcesEdit

Primary sources may be searched for possible additional information perhaps not yet evaluated by SIMBAD or not presently considered close enough to alpha Antliae to be the star.

Further down the SIMBAD page for "* alf Ant" is a list of "Identifiers (30)". Primary source literature may use any of these to include the star in their experimental observations. From the 'External links' near the bottom of this page, try a search with text something like "alpha antliae" "X-rays" or "X-ray".


  1. on Bing with "alpha antliae" and "X-ray" there is "α Ant (Alpha Antliae) - Star - SKY-MAP" which mentions "X-ray sources". A browser search of the page using "x-ray" highlights ten entries below the article title: "Hybrid stars and the reality of "dividing lines" among G to K bright giants and supergiants."[2] Does the article mention "alpha antliae" or "α Ant"? Is the star directly observed as an X-ray source? Do the authors suggest that based on lines observed that alpha Antliae probably is an X-ray source? Do you believe an entry should be made in the section "X-ray source in Antlia"?

Changing an entryEdit

From your analysis of Alpha Antliae so far, is it an X-ray source?

If you believe the answer to the above question is "no", you can annotate the entry to indicate that you checked at least a couple primary sources and so far the star is not an observed X-ray source. Or, you can leave the entries as is and try another star.

If you believe alpha Antliae is an X-ray source you can edit the "X-ray source in Antlia" and make an entry. Specifically, the article Bing located is [1] and you can annotate your entry with it if you want to.

X-ray sources in AntliaEdit

  1. 1RXS J092856.0-354610 Position Reference:1999A&A...349..389V[3] "the all-sky survey [was] performed during the first half year (1990/91) of the ROSAT mission."[3] Marshallsumter (talk) 19:38, 26 February 2012 (UTC)
  2. delta Antliae (HD 90972, HR 4118)[4], log Lx = 29.86.[4] Detected in the same ROSAT all-sky survey during the first half year (1990/91).[5] Marshallsumter (talk) 17:38, 30 May 2012 (UTC)
  3. Antlia Cluster: Using the now obsolete scientific satellite ASCA, X-ray observations show the cluster is almost isothermal, with a mean temperature of kT ~ 2.0 keV.[6] "We observed the Antlia cluster with ASCA on 1997 June 8-9."[6] Marshallsumter (discusscontribs) 03:30, 12 March 2013 (UTC)
  4. "The X-ray properties of the Antlia cluster are peculiar. Pedersen et al. (1997) used ASCA observations centered on NGC 3258, where they clearly found extended X-ray emission. They also noted that the 1.7 keV hot gas extends towards NGC 3268 and they excluded this part from their investigation. The emission peak is offset by 1.1' from NGC 3258 and does not coincide with any other galaxy."[7] and "We obtained a 22,400 s exposure of the NGC 3258 group of galaxies with ASCA in 1994 May."[8] Marshallsumter (discusscontribs) 20:41, 13 March 2013 (UTC)
  5. The Einstein X-ray Observatory satellite "operated for 2 1/2 years beginning in 1978 November [13] ... During its operation, the [Imaging Proportional Counter] IPC obtained nearly 4100 images"[9] which included 1E 1026.7-3521, NGC 3258. Marshallsumter (discusscontribs) 01:36, 14 March 2013 (UTC)
  6. At top right is a ROSAT X-ray image of a SNR in Antlia from the ROSAT all-sky survey published in 1997.[10] --Marshallsumter (discusscontribs) 21:04, 20 May 2014 (UTC)
  7. During the operation of the Uhuru X-ray observatory satellite it located and observed a source cataloged at B1950.0 2U 1005-32.[11] This is in the constellation Antlia. The Uhuru was launched on December 12, 1970. And, the catalog containing 2U 1005-32 was received for consideration and publication on 4 May 1972.[11] --Marshallsumter (discusscontribs) 02:38, 5 February 2016 (UTC)

Non-X-ray sources in AntliaEdit

  1. alpha Antliae 2012.01.07CET19:20:27 SIMBAD article "* alf Ant". Marshallsumter (talk) 17:42, 26 February 2012 (UTC)
  2. epsilon Antliae 15 December 2010 at 20:53 Wikipedia article. Marshallsumter (talk) 18:25, 26 February 2012 (UTC)
  3. delta Antliae 2012.05.30CEST18:12:44 SIMBAD article "* del Ant -- Star in double system". Marshallsumter (talk) 17:47, 30 May 2012 (UTC)


  1. X-ray source 2U 1005-32 may have been the first X-ray source detected in the constellation Antlia.

See alsoEdit


  1. Joseph Lazio. Astronomers Detect Powerful Bursting Radio Source Discovery Points to New Class of Astronomical Objects. http://www.nrao.edu/pr/2005/newsource/. 
  2. D. Reimers, M. Hünsch, J.H.M.M. Schmitt, and F. Toussaint (June 1996). "Hybrid stars and the reality of "dividing lines" among G to K bright giants and supergiants". Astronomy and Astrophysics 310 (6): 813-24. 
  3. 3.0 3.1 W. Voges, B. Aschenbach, Th. Boller, H. Bräuninger, U. Briel, W. Burkert, K. Dennerl, J. Englhauser, R. Gruber, F. Haberl, G. Hartner, G. Hasinger, M. Kürster, E. Pfeffermann, W. Pietsch, P. Predehl, C. Rosso, J.H.M.M. Schmitt, J. Trümper, and H.U. Zimmermann (September 1999). "The ROSAT all-sky survey bright source catalogue". Astronomy and Astrophysics 349 (9): 389-405. http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1999A%26A...349..389V&link_type=ARTICLE&db_key=AST&high=. Retrieved 2012-02-26. 
  4. 4.0 4.1 S. Hubrig, D. LeMignant, P. North, and J. Krautter (June 2001). "Search for low-mass PMS companions around X-ray selected late B stars". Astronomy and Astrophysics 372 (6): 152-64. doi:10.1051/0004-6361:20010452. http://arxiv.org/pdf/astro-ph/0103201v1. Retrieved 2012-05-30. 
  5. T.W. Berghöfer, J.H.M.M. Schmitt and J.P. Cassinelli (September 1996). "The ROSAT all-sky survey catalogue of optically bright OB-type stars". Astronomy and Astrophysics Supplement Series 118 (9): 481-94. http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2001A%2526A...372..152HFUL. Retrieved 2012-05-30. 
  6. 6.0 6.1 Kazuhiro Nakazawa, Kazuo Makishima, Yasushi Fukazawa, Takayuki Tamura (August 2000). "ASCA Observations of a Near-by Cluster in Antlia". Publications of the Astronomical Society of Japan (Tokyo, Japan: PASJ) 52: 623–630. http://adsabs.harvard.edu/abs/2000PASJ...52..623N. Retrieved March 4, 2012. 
  7. B. Dirsch - T. Richtler - L. P. Bassino (September IV 2003). "The globular cluster systems of NGC 3258 and NGC 3268 in the Antlia cluster". Astronomy & Astrophysics 408 (3): 929-39. doi:10.1051/0004-6361:20031027. http://www.aanda.org/index.php?option=com_article&access=standard&Itemid=129&url=/articles/aa/full/2003/36/aah4465/aah4465.html. Retrieved 2013-03-13. 
  8. Kristian Pedersen, Yuzuru Yoshii and Jesper Sohher-Larsen (August 10 1997). "A New Measurement of the Baryonic Fraction Using the Sparse NGC 3258 Group of Galaxies". The Astrophysical Journal 485 (1): L17-20. http://adsabs.harvard.edu/abs/1997ApJ...485L..17P. Retrieved 2013-03-13. 
  9. Aaron D. Lewis, John T. Stocke, and E. Ellingson and Eric J. Gaidos (February 20, 2002). "New X-Ray Clusters in the Einstein Extended Medium-Sensitivity Survey. I. Modifications to the X-Ray Luminosity Function". The Astrophysical Journal 566 (2): 744-70. http://iopscience.iop.org/0004-637X/566/2/744/fulltext/. Retrieved 2013-03-13. 
  10. P. R. McCullough, Brian D. Fields, and Vasiliki Pavlidou (September 1, 2002). "Discovery of an Old, Nearby, and Overlooked Supernova Remnant Centered on the Southern Constellation Antlia Pneumatica". The Astrophysical Journal 576: L41-4. http://iopscience.iop.org/1538-4357/576/1/L41/pdf/1538-4357_576_1_L41.pdf. Retrieved 2014-05-20. 
  11. 11.0 11.1 R. Giacconi, S. Murray, H. Gursky, E. Kellogg, E. Schreier, and H. Tananbaum (December 1, 1972). "The Uhuru Catalog of X-ray Sources". The Astrophysical Journal 178 (12): 281-308. doi:10.1086/151790. http://adsabs.harvard.edu/abs/1972ApJ...178..281G. Retrieved 2014-07-06. 

Further readingEdit

External linksEdit

{{Radiation astronomy resources}}{{History of science resources}}