Post date: 27-Mar-2009 16:51:49
Ronald Downes is an astronomer at the Space Telescope Science Insitute, and has spent his entire career (in one way or another) on HST. His thesis was a survey for CVs (he expected to find ~200, and found 1!), and has continued doing discovery-type work ever since. Besides CVs, he has worked on quasars, supernova remnants, and more recently carbon stars. Ron's observing has been done at University of California and National observatories, as well as with HST.
CVnet: What is the story behind how and why the original scientific paper, Downes and Shara 1993, PASP 105, 127; Downes, Webbink, and Shara 1997, PASP 109, 345, turned into an online catalog and atlas?
*Ron: There were two main reasons for the decision to go on-line.
First, publishing >100 page papers is very time-consuming (for example, getting all the formatting correct) and expensive. But more importantly, new objects and updated information were appearing so fast that the catalog was woefully out-of-date almost the day it was published. Also, the original aim of the catalog was to have one place were people could go for basic information on CVs, and since we did not reproduce all the finding charts with each edition, I was concerned that the catalog was getting too fragmented.
CVnet: The Downes et al, Living Edition of the Catalog and Atlas of Cataclysmic Variables is a continuous work in progress. Who are the others, the 'et al', involved in updating, researching and revising the catalog?
*Ron: My original collaborator was Mike Shara, who provided a double-check on the catalog entries, but more importantly, got me access to the HST Guide Star Catalog images, which allowed us to provide updated coordinates and the finding charts. Ron Webbink was the next to join, providing updated coordinates, revised/new identifications, and proper motions for many objects. Finally, Hilmar Duerbeck, who provided identifications for novae (most but not all from his published nova catalog), and Hans Ritter and Ulrich Kolb, who provide the period information (based on their separate period catalog), joined the team. I would be remiss if I did not identify the technical staff here at STScI who made the web site possible - Anne Gonnella and Steve Hulbert - and who help me with maintainance and enhancements - Mike Wiggs.
CVnet: What is the 'standard' for inclusion in the atlas? There seem to be many unconfirmed or unknown types and stars. Is this meant to be a clearing house for all 'possible' CVs or is there a higher standard?
*Ron: The standard for inclusion is either publication in a refereed journal, or a definitive report on an object (either from a newsgroup like cvnet or from a direct email sent to me). The catalog is indeed meant to be a clearinghouse for all objects confirmed or proposed to be CVs, although only those objects proposed in the published literature make it into the catalog.
CVnet: If someone discovers a potential CV or determines a typology from observations of superhumps or the lack of superhumps during an outburst, how is the type determination made for inclusion in the catalog? Do results of observations or discoveries from online data such as ASAS need to be published in some "official" form to be included in the atlas?
*Ron: As I mentioned above, information gets included in the catalog either from published results, or from definitive reports. As long as I hear about it, it can (potentially) go into the catalog.
CVnet: Along the same lines, why are there non-CVs in the catalog? Is this to eliminate or elucidate errors in other published works?
*Ron: The catalog includes all objects that are either CVs or were at one time classified as CVs. The non-CVs were left in so that people who only knew of the CV classification would not waste time observing the object. I would also note that the works that originally proposed the CV classifications are not necessarily in error, as the information they had may have been consistent with the objects being CVs. However, it is new information that has allowed us to refine the classification.
CVnet: There are types and sub-types of CVs recognized by different factions in the study of CVs. For example, UGSU sub-type ER, UGSU(ER), is recognized as a distinct sub-group by some, but not officially recognized in the GCVS or many other places. Another one is SW Sex stars. This is a group of stars that has its own websites and devotees, yet it is not recognized as a sub-set or type of CV by either the GCVS or Downes et al. Why? What is the Downes et al criteria for inclusion as a sub-set or type?
*Ron: I started with the GCVS classifications, and at the time of the first edition, added what I thought were established sub-types. The GCVS is still the official keeper of variable star classifications, so I would only accept an new sub-type (not in the GCVS) if I thought the CV community as a whole accepted it. For example, I added the VY Scl sub-type for NLs.
CVnet: Looking at the bigger picture, how do you wish or hope the online catalog will benefit astronomy in general? Are there uses or potential uses of the catalog that have not yet been realized?
*Ron: I am hoping that the catalog serves the CV community, both professional and amateur, to aid in obtaining data on CVs. I have already seen papers come out from people who are trying to obtain modern spectra for the many objects without spectroscopic data, and those who are trying to confirm the CV nature of little-studied objects. And others who are trying to recover the quiescent counterparts to objects where there is no certain identication. I hope that having the catalog available can facilitate these studies, which will allow us to get a better picture of what CVs are, and how they work.
CVnet: What can CVnet observers and participants do to contribute to the future and potential of the online CV catalog and atlas?
*Ron: Just continue making your observations and reporting them. I subscribe to cvnet-discussion, and always welcome direct emails on new discoveries or updated identications/classifications.
CVnet: You've been great to discuss this with us. Will you stay in touch, and let us know about future developments on the website?
*Ron: I certainly will!