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Gum data

Submitted by Kevin Jardine on 13 September, 2009 - 13:14

As I've been going through my commentary on the RCW catalog, I've come to realise that there are several dubious or erroneous cross identifications in the RCW catalog, especially with regard to objects in the Gum catalog. In several cases, it appears that Colin Gum was actually referring to a different object or only part of the object as later defined by RCW. To deal with this, I'm going to put up a map showing the locations and extents of all the objects in the Sharpless, RCW and Gum catalogs.

My commentary on the Gum catalog currently uses the coordinates for these objects given in SIMBAD. However, these coordinates are often derived by SIMBAD using identifications with other nebulae and do not reflect the actual data given in Gum's original catalog. Unlike the Sharpless and RCW catalogs, Gum's original catalog data is not available through Vizier, so as a first step, I have manually entered Gum's original data for each of the 97 entries in his catalog into an Excel-format spreadsheet.

Gum supplied 1900 epoch RA and Declination data for these objects. I've used the Python ephem library to convert these into current l and b galactic coordinates and added these to the spreadsheet as well. (Note that the galactic coordinates supplied by Gum in his original catalog are based on the old Lund pole system and I have not included these in the spreadsheet.)

You can find the Gum spreadsheet here. I'll post another blog entry when the nebula map is ready.

Milky Way Explorer revised

Submitted by Kevin Jardine on 24 July, 2009 - 18:12

I've simplified the interface, fixed a few bugs, and most importantly, added several new datasets to the Milky Way Explorer. There is now context-sensitive help, so you can get information on each map you are looking at by clicking the Help button.

I've tested the interface in Internet Explorer 7, Firefox 3.5 and Safari for Windows.

You can go directly to the Milky Way Explorer here but please read the documentation first if you haven't used it before.

Astronomical conservatism

Submitted by Kevin Jardine on 30 May, 2009 - 11:37

I'm amazed sometimes by the cultural conservatism I see amongst scientists, including many astronomers. A case in point is Bo Reipurth's wonderful recent Handbook of Star Forming Regions (you can see the contents of Volume 1 and Volume 2). Reipurth is a respected Danish astronomer (currently based in Hawaii) and editor of the Star Formation Newsletter.

There has been an explosion of recent results on star-forming regions, driven in part by the amazing images from space telescopes, especially Chandra (X-rays) and Spitzer (infrared). It is definitely time for a survey that brings this all together. Many of the individual chapters of the Handbook are available for free as preprints (you can google for them or use arXiv). From this content I can see that the Handbook is an amazing resource.

It seems obvious, however, that this survey would have been far better implemented as a website rather than a printed Handbook. As a website, it would have been easy to update, easy to link to all the relevant references through the ADS, easy to search via Google, and could have made use of modern interactive map interfaces such as the Milky Way Explorer to display the objects discussed. Although the content is available as PDFs, these have practically all of the same limitations as print publications and none of the advantages of websites.

Granted, the Astronomical Society of the Pacific can charge for the Handbook (an eye-popping 160 US dollars for both volumes), but they also could have charged for website access (at least for a limited period), and in any case, I doubt that the publishers stand to make much money from this publication.

I suspect that the Handbook has been printed because of a quirk in the sociology of academic science. Specifically, websites are not yet considered to be citeable publications, and it would have been impossible for Reipurth to convince the dozens of astronomers who collaborated to produce the Handbook chapters to spend that considerable time on something that they could not add to their scientific bibliographies.

I can only hope that the Astronomical Society of the Pacific will see the light at some point in the future and rework this content (or perhaps an updated and expanded version of it) into what would be a fascinating, beautiful and extremely useful website.

Sharpless commentary completed

Submitted by Kevin Jardine on 24 May, 2009 - 10:46

It's been almost four years since I created the Sharpless catalog section of this website. I can finally announce that there is a commentary for each entry in the Sharpless catalog.

The Sharpless commentary would not have been possible without the work of Veta Avedisova and her colleagues at the Institute of Astronomy, Russian Academy of Sciences, in Moscow. Avedisova's crucial paper identifying ionising stars for many HII regions and her recent Catalog of Star-Forming Regions in the Galaxy have brought together a huge amount of information on many Milky Way objects. In so far as the world's astronomers have succeeded in creating an Encyclopedia Galactica, Veta Avedisova is its editor-in-chief.

I'm now moving on to finish my commentaries on the RCW and Gum nebulae and, of course, I will add new research results on Sharpless objects as they become available. Even now, 50 years after the publication of the final Sharpless catalog, there are many unresolved mysteries concerning these objects and at some point I'll put up a special article listing some of these.


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