Lynds Target Selection

I haven't done this legwork yet because I thought you might want to be involved - finding a good target for observation is a substantial part of doing science! :)

Ideally, we'd pick a target for our observation using a combination of

• searching ADS and/or SIMBAD for existing literature .... we want something that doesn't have a LOT of other references, but some references are fine - if someone else has already assembled data on an object, we might be able to use those data and/or results - we just don't want something that has already been "done to death." (page from the wiki on literature searching)
• checking POSS and other existing multi-wavelength data to see what the object looks like in those bands .... does it look thick and dark in the optical? bright in the infrared? Both of those things suggest that it will be interesting with Spitzer. Something that looks diaphanous in the optical will likely turn out to be completely transparent with Spitzer. (page from the wiki on introduction to data at other wavelengths; you can also do this with Leopard -- see next item.)
• and, checking to see if it is or is not in the Spitzer archive .... you need to use Leopard to do this. (page from the wiki on searching the archive using Leopard-- NB: "searching the archive to see what is there" is the same thing as "downloading data" except that when you search to see what is there, you don't actually download the data, you just see that there is something there.) Also, note that just because there is data already in the Archive on a given cloud doesn't mean it's a BAD thing, just that it's not a good thing for a new proposal. You should make a note of the "nice" ones you find, because you can go grab the data as soon as the data are public.

My original thoughts on good targets were the following three:

• LDN 470
• LDN 1225
• LDN 880 (but maybe too diaphanous)

And, at the AAS, you guys also came up with

• LDN 1340

The master list of objects that I worked from is here, courtesy of Babar Ali. Note that these are all opacity class 5 objects. Opacity class 5 or higher is what we probably want for Spitzer observations. None of these have many references in ADS. This is not meant to be a comprehensive list by any means, just a place to start. If you want to instead start with the complete Lynds Dark Nebulae catalog, it's here (the data are linked as "online data" or something similar).

Please post your thoughts and reactions to each of these targets, and any new ones you think are viable candidates for observation. For example, you might post a gif or jpeg of the POSS image you found, or a summary list of references (e.g., "3 papers besides Lynds, one radio, others submm" or whatever). Note the syntax I'm using to post comments on LDN 1340 below -- this is a method suggested by the Oil City folks, and I think it works really well to follow the conversation. See the help page linked from the left (above the search box) for hints on how do this.

--Guastella 20:48, 8 January 2008 (PST) Here is the article I mentioned in our meeting earlier today. (this is the one that looked in radio at optically-selected cores and reported which ones were "empty.")

THE ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 123:233È250, 1999 July (1999. The American Astronomical Society. All rights reserved. Printed in U.S.A. A CATALOG OF OPTICALLY SELECTED CORES CHANG WON LEE AND PHILIP C. MYERS [...] This didn't format well. Please let me know if there is a better way to send papers Thanks Pete [END]

(--Rebull 09:25, 9 January 2008 (PST) he's right, this didn't format well, so I replaced it with a link directly to ADS, from which you can get the complete article - there's no access restrictions on it, and if you go there, you can get the originally formatted PDF or the html. ADS link to the Lee and Myers paper [END] )

LDN 1340

--Rebull 20:14, 8 January 2008 (PST) Here's a summary of the latest developments on this object:

One of you (Peter?) suggested this object - and it was a fabulous suggestion. Beautiful in the optical, with IRAS sources, a handful of existing literature, and no Spitzer. Perfect! The icing on the cake was that it's visible in the Spring.

One of you (Peter again?) noticed that there was another AAS poster from 2005 on this object. I mentioned that I knew 2 of the authors (JoAnn O'Linger and Grace Wolf-Chase). Not 2 hours after leaving you, I ran into them. One thing I didn't mention in the context of searching the archive is that there is an open call for proposals out now, eg., there are ~700 proposals for objects that are currently being reviewed, and 20% of them will get their targets approved by March. To some extent, since you're putting in a proposal more or less now, you kind of trump them. On the other hand, it's never good to make enemies.... So, it turns out that JoAnn and collaborators have submitted a proposal to map this region over 1 square degree. There's no guarantee that their data will actually be taken this cycle (before we run out of cryogen in Spring 2009), but at the same time, we probably won't be able to ask for a full square degree (it would take too much time). We could pick a subregion to focus on, or we could find another target entirely.

I'll continue to talk to JoAnn (we had just a brief conversation today), and if I can get her posters (one from before, one from this meeting!), I'll post them here.

[END]

--Guastella 20:48, 8 January 2008 (PST) In case we are still looking at this here is the 2005 Abstract Submillimetre Observations of an Intermediate-Mass Star Forming Cloud Core J. O’Linger, G. H. Moriarty- Schieven, and G. A. Wolf-Chase

ADS link to AAS abstract

ADS link to PPV abstract

--Rebull 09:37, 9 January 2008 (PST) I talked to JoAnn again today, and she thinks that maybe doing just a piece of the cloud would be a good idea. She showed me some of her supporting data, and indeed this is a really cool area. We could do just a part of it now, and eventually, she'll map the rest of the cloud as well.

Here's her poster from today: Media:joann2008poster.pdf

[END]

LDN 951

From: cdewolf@chsd.us How does LDN 951 look? Assuming I did my query right, it also hasn't been looked at by Spitzer. I found it on a list of LDNs that have visual opacities of 6 in a paper by Visser et. al, 2002. There's another, but it doesn't look as interesting. Cris L. DeWolf

--Rebull 14:00, 9 January 2008 (PST) ooh, this is a nice one! you're right, it doesn't have any Spitzer observations yet. This might very well be a good candidate! [END]

--Dewolf 06:00, 12 January 2008 (PST)There was a study of IRAS associations with dark clouds (Parker, N.D., 1988) that appears to indicate a good chance of there being a YSO in LDN 951. Here's a link to the article. [1] [END]

Other targets

--Rebull 11:42, 9 January 2008 (PST) I found two posters today on Lynds clouds - L1221 and L988e. L1221 has Spitzer data which is pretty cool; L988 doesn't have any Spitzer data. Take a look at the other bands and references and see if it would be interesting.... [END]

--Rebull 13:44, 14 January 2008 (PST) David added some stuff to the talk page [END]

Observing time

--Rebull 13:59, 14 January 2008 (PST) David asked re: time to cover area. A map I have here that goes about the depth we want covers about 0.6deg x0.6 deg with IRAC takes 1.5 hrs, and more or less the same area takes another 1.4 hrs with MIPS. 3 hrs is probably too much to ask for, especially if you want to ask for more than one cloud. less than that size, 0.3 deg x 0.3 deg, with IRAC takes 0.4 hrs, and up to 0.7 hrs with MIPS. (i can get clever and try to make that less time, but this is the lowest-energy solution.) For an irregularly-sized thing like LDN 951, i can get creative and make something other than a square map, but it takes longer for me to design. so we need to decide if (a) we have something really cool we want to completely map, or (b) two smaller things (could be pieces of a large thing) we want to map to compare them. Note that the object above, LDN 1340, is more like ~1 degree x ~1 degree, so we'd have to do just a small piece of it. [END]