An observing plan containing the Arakelian Galaxies has been posted recently to the Deep-Sky Planner Observing Plan Library (licensed users only.) This plan should be of particular interest to galaxy hunters, so more background is included here.
Russian astrophysicist Marat Arakelian published a paper in 1975 in which he studied the correlation between high surface brightness (HSB) galaxies and active galactic nuclei. Arakelian defined HSB as 22 magnitudes per square arc second (mpsas) or brighter.
Deep-Sky Planner shows surface brightness (SB) for galaxies when possible. The value comes either from catalogs when it is available, or it is calculated using a formula that is a little different from that used by Arakalian. Because of these differences, the plan has some SB values that are dimmer than 22. Most of the galaxies in the plan are smaller than 1 arc minute in size, thus contributing to high surface brightness. With this in mind, the observing plan contains about 500 of 591 galaxies with SB values of 22 or brighter. These galaxies (with SB <= 22) should be bright enough to be seen in large amateur telescopes in a dark sky location - those with skies perhaps 20.5 mpsas or darker.
Arakelian studied galaxies no further south than -3 degrees declination, so they are visible to northern hemisphere observers, and most are visible to observers at moderately southern latitudes.
The study found that there were more elliptical and lenticular galaxies in the study sample than one might find in a random sample, thus proving that there was a correlation between high surface brightness and active galactic nuclei. Arakelian's study was an important basis for further research. Arakelian himself had only a few years to explore the matter further since he died in 1983 at the young age of 52.
24 February 2015
05 February 2015
Integrated Flux Nebulae
I recently read about integrated flux nebulae (IFN), whose name was coined by amateur astronomer Steve Mandel. Steve photographed and cataloged a number of objects at high galactic latitudes that were wispy, dusty nebulae, though uncatalogued by professional astronomers.
A quick visit to Steve's web site reveals his personal pursuit of identifying these objects, and what his research has uncovered about them. Steve's work on these objects has been recognized by the American Astronomical Society (2008 Chambliss Award for Amateur Achievement) and the Astronomical Society of the Pacific (2008 Amateur Achievement Award). Professional astronomers have begun investigating these objects based on Steve's work.
In a recent email from Steve, he explains that the catalog will be renamed "Mandel Catalogue of Unexplored High-Latitude Galactic Dust Nebula". He continues his work on this project.
An observing plan containing the current list of integrated flux nebulae has been uploaded to the Plan Library which is available to licensed users of Deep-Sky Planner. It contains the list of objects and Steve's comments about each. Steve has kindly granted permission to use this information in Deep-Sky Planner.
A quick visit to Steve's web site reveals his personal pursuit of identifying these objects, and what his research has uncovered about them. Steve's work on these objects has been recognized by the American Astronomical Society (2008 Chambliss Award for Amateur Achievement) and the Astronomical Society of the Pacific (2008 Amateur Achievement Award). Professional astronomers have begun investigating these objects based on Steve's work.
In a recent email from Steve, he explains that the catalog will be renamed "Mandel Catalogue of Unexplored High-Latitude Galactic Dust Nebula". He continues his work on this project.
An observing plan containing the current list of integrated flux nebulae has been uploaded to the Plan Library which is available to licensed users of Deep-Sky Planner. It contains the list of objects and Steve's comments about each. Steve has kindly granted permission to use this information in Deep-Sky Planner.
31 January 2015
Wide-Field Observing
I recently posted an observing plan to the Deep-Sky Planner Plan Library containing most of the objects that appear in the "Wide-Field Wonders" article in the 2013 RASC Observer's Handbook. (The article also appears in the 2015 edition.) While most of the objects are nebulae and clusters, a few are more esoteric objects that aren't found in typical catalogs - things like molecular clouds. This plan contains an excellent variety of imaging and viewing targets, so I encourage readers to check out the article to get background information.
Wide-field observing (both visual and imaging) generally requires a rich-field telescope, binoculars, or a fairly fast telescope with a long focal length eyepiece. These objects often have low surface brightness, so a dark location is definitely indicated.
Wide-field observing can be a nice change of pace if your usual deep-sky observing includes galaxies, planetary nebulae and such. For example, I've observed the Veil Nebula in Cygnus dozens of times with various telescopes. I always enjoy viewing it with a UHC filter and magnification around 100x. The telescope I use most often these days is a 14.5" f/4.5 reflector. My rather ancient 20mm Nagler eyepiece produces magnification of 96x with a field of view of about .86° with this telescope. I've used this combination of equipment for several years, so the end result is somewhat expected.
I got a new lower power eyepiece a year or so ago that was a game-changer on things like the Veil. The new eyepiece is a 31mm Nagler which produces 61x with FoV of 1.3°. It turns out that the view with the 31mm eyepiece allows me to see most of the nebula at once. The view with the 20mm requires a lot of scanning around to view the entire nebula. While the detail is much greater with the 96x view, the ability to 'get it all' at 61x is a welcome new capability. I've also observed the Veil through a friend's Tele Vue-NP101 (101mm, f/5.4) with a 31mm Nagler. The view was stunning and quite different from my usual result. That view really inspired the purchase of the 31mm eyepiece.
From this I think it is fair to suggest that we get into familiar patterns with our observing - both imaging and visual. A simple change like using a different eyepiece can produce a very different view, even with an object that is very familiar. Perhaps we should take the next step with this by pursuing an observing plan that includes objects well off of our beaten path. The "Wide-Field Wonders" plan may be such a refreshing change of fare.
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| Observer's Handbook from Royal Astronomical Society Canada |
Wide-field observing (both visual and imaging) generally requires a rich-field telescope, binoculars, or a fairly fast telescope with a long focal length eyepiece. These objects often have low surface brightness, so a dark location is definitely indicated.
Wide-field observing can be a nice change of pace if your usual deep-sky observing includes galaxies, planetary nebulae and such. For example, I've observed the Veil Nebula in Cygnus dozens of times with various telescopes. I always enjoy viewing it with a UHC filter and magnification around 100x. The telescope I use most often these days is a 14.5" f/4.5 reflector. My rather ancient 20mm Nagler eyepiece produces magnification of 96x with a field of view of about .86° with this telescope. I've used this combination of equipment for several years, so the end result is somewhat expected.
 |
| 14.5" f/4.5 Reflector |
I got a new lower power eyepiece a year or so ago that was a game-changer on things like the Veil. The new eyepiece is a 31mm Nagler which produces 61x with FoV of 1.3°. It turns out that the view with the 31mm eyepiece allows me to see most of the nebula at once. The view with the 20mm requires a lot of scanning around to view the entire nebula. While the detail is much greater with the 96x view, the ability to 'get it all' at 61x is a welcome new capability. I've also observed the Veil through a friend's Tele Vue-NP101 (101mm, f/5.4) with a 31mm Nagler. The view was stunning and quite different from my usual result. That view really inspired the purchase of the 31mm eyepiece.
 |
| TeleVue's 31mm Nagler |
From this I think it is fair to suggest that we get into familiar patterns with our observing - both imaging and visual. A simple change like using a different eyepiece can produce a very different view, even with an object that is very familiar. Perhaps we should take the next step with this by pursuing an observing plan that includes objects well off of our beaten path. The "Wide-Field Wonders" plan may be such a refreshing change of fare.
01 January 2015
Robert Trumpler's Open Clusters
An observing plan called the Trumpler Clusters was created recently for Deep-Sky Planner and posted to the Plan Library. Licensed users can view and download the plan by logging into the Deep-Sky Planner Community and browsing for the plan in the Library (Help | Community Page).
Open clusters are wonderful observing targets during the present season. Some of the Trumpler clusters are a bit dim for common binoculars, but a telescope serves well when observing them. The Trumpler clusters are located between declinations +63 and -63, so many are visible to both northern and southern hemisphere observers.
I have looked for Robert Trumpler's original paper for years without finding it. Phil Harrington's recent article on Cloudy Nights included a link to Trumpler's original paper which is available on ADS at Harvard. (Thanks go to Phil for providing this!)
Trumpler's paper was published in 1930 and sought to define all known open clusters. Thirty-seven of the objects in the list were unknown when the paper was written, and these have become known as the Trumpler clusters. All but Trumpler 36 are still recognized in today's literature. Trumpler 36 is a bit of a riddle, although it seems to be IC 1311. Trumpler's paper also included a study of cluster diameter, distance and magnitude of member stars. It's a very interesting paper to read even some 85 years later. Any dedicated observer of open clusters should have a look at it.
The observing plan that appears in the Deep-Sky Planner library includes updated coordinates and size information from "Optically Visible Open Clusters Catalog" (Dias+, 2002-2012). Trumpler's original classifications are also included in the plan. The well-known Trumpler classification system encodes concentration, richness and brightness as follows:
Concentration
I=detached cluster, strong concentration
II=detached cluster, little concentration
III=detached cluster, no concentration
IV=undetached cluster
Brightness
1=equal brightness
2=medium range of brightness
3=bright & faint members
Richness
p=poor, < 50 members
m=moderate, 50-100 members
r=rich, > 100 members
Enjoy observing the Trumpler Clusters in the new year!
Open clusters are wonderful observing targets during the present season. Some of the Trumpler clusters are a bit dim for common binoculars, but a telescope serves well when observing them. The Trumpler clusters are located between declinations +63 and -63, so many are visible to both northern and southern hemisphere observers.
I have looked for Robert Trumpler's original paper for years without finding it. Phil Harrington's recent article on Cloudy Nights included a link to Trumpler's original paper which is available on ADS at Harvard. (Thanks go to Phil for providing this!)
 |
| Trumpler 36 / IC 1311 © 1995 by the Association of Universities for Research in Astronomy, Inc |
The observing plan that appears in the Deep-Sky Planner library includes updated coordinates and size information from "Optically Visible Open Clusters Catalog" (Dias+, 2002-2012). Trumpler's original classifications are also included in the plan. The well-known Trumpler classification system encodes concentration, richness and brightness as follows:
Concentration
I=detached cluster, strong concentration
II=detached cluster, little concentration
III=detached cluster, no concentration
IV=undetached cluster
Brightness
1=equal brightness
2=medium range of brightness
3=bright & faint members
Richness
p=poor, < 50 members
m=moderate, 50-100 members
r=rich, > 100 members
Enjoy observing the Trumpler Clusters in the new year!
21 July 2014
Deep-Sky Planner Q&A Webinar - July 2014
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| July Webinar - Double Star Designations |
Search tools and methods were discussed, including searching by Bayer number, WDS and CCDM numbers, and using wildcards in designations. A few advanced methods were also discussed. The webinar lasted 16 minutes.
The webinar is available now for replay viewing at:
Viewers that are logged into their Google+ accounts can leave comments about the webinar on the deepskyplanner Google+ page or on the deepskyplanner YouTube channel.
Thanks for watching!
24 March 2014
Deep-Sky Planner Q&A Webinar
Knightware held a Deep-Sky Planner Q&A webinar on Saturday, March 22. It was delivered worldwide via Google+ Hangouts. The broadcast allowed Knightware to answer users' questions directly as we would when speaking face to face at star parties and trade shows.
The webinar replay is available now at several locations:
- Webinar Event page
- deepskyplanner Google+ page
- deepskyplanner Youtube channel
- Deep-Sky Planner video library
The second question was much like the first, except that the user was interested in double stars and wanted to specify a range of separation angles. The demonstration proceed much like the first, except that a maximum separation angle of 2 arc seconds was used to create the initial list. These results were copied to an observing plan so that the user could apply the same real-time filters and sort options as described above.
The third and final question was a bit different from the previous ones. The user wanted to make an observing list for a public observing session. Since the public is usually interested in brighter objects, we created a deep-sky search document and searched for objects in the Messier catalog that were at least magnitude 9 or brighter. A time and place for the ephemeral calculations was selected and the results were limited to objects at an altitude of at least 20 degrees. The resulting list could be sorted and filtered further as needed.
Over the course of the webinar, we showed some other features that helped users, like object drag and drop between reports, DSS image acquisition, daily object altitude graphs and object cross reference lookup (which provided detailed data for a variable star that also appeared in the Carbon Star catalog). Of further interest to star observers, we showed predicted date & time of light extrema for variables and high precision ephemerides for double stars.
Knightware plans to have further webinars - perhaps quarterly. We will solicit questions from users in advance so that demonstrations are concise. Next time, we will accept comments and minor questions from viewers during the webinar through Google+. While anyone can view the webinar, it should be noted that viewers will need to have a Google+ account and follow the deepskyplanner Google+ page to submit questions during the broadcast. They will also receive an invitation to the webinar automatically.
Special thanks go to our friend Michael Kidd and the folks at Astronomy magazine for answering questions about using Google+ for the webinar. Your help made the webinar possible.
03 February 2014
Current Studies of Light Pollution
Phyllis Lang, owner of Knightware, recently gave a presentation on Light Pollution at the North Carolina Museum of Natural Sciences in Raleigh. Some of the content had local relevance (City of Raleigh ordinances), but most was of a more general nature.
The presentation defined light pollution and its unwanted effects - economic, environmental and astronomical. Regardless of the effect that motivated them, people were interested in taking simple steps to mitigate light pollution. These easy steps were mentioned as effective changes that citizens can take:
Measuring light pollution is a vital component in understanding light pollution - in both what it affects and how. Citizen scientists can help with this task by participating in the Globe at Night and Great Worldwide Star Count projects. These are easy projects for families and school groups, and the results are useful to researchers worldwide.
Large scale studies can be conducted by institutions and governments. These studies are supported by objective methods of measuring light pollution which are readily available now. Off-the-shelf equipment, such as Unihedron's Sky Quality Meter and Knightware's SQM Reader Pro are being used in a surprising number of studies worldwide. Some examples include:
While astronomers have used light pollution studies for years to plan the locations of their observatories, many other issues are being studied now. The leading issues being studied are economic waste, harm to animals, and the inability to view the natural night sky. One of the most surprising issues studied recently was the effect of light pollution on urban air chemistry; that is, air pollution. This one was conducted by the National Oceanic and Atmospheric Administration and the University of Colorado.
Light pollution affects more than most people realize, and the list of problems caused by it is growing. Researchers will continue to explore this issue, and concerned citizens can take effective action today to mitigate the problem.
The presentation defined light pollution and its unwanted effects - economic, environmental and astronomical. Regardless of the effect that motivated them, people were interested in taking simple steps to mitigate light pollution. These easy steps were mentioned as effective changes that citizens can take:
- Aim outdoor lighting downward.
- Shield outdoor lighting fixtures. Suggestions are available from the International Dark-Sky Association
- Turn off outdoor lighting when not actually needed.
Measuring light pollution is a vital component in understanding light pollution - in both what it affects and how. Citizen scientists can help with this task by participating in the Globe at Night and Great Worldwide Star Count projects. These are easy projects for families and school groups, and the results are useful to researchers worldwide.
Large scale studies can be conducted by institutions and governments. These studies are supported by objective methods of measuring light pollution which are readily available now. Off-the-shelf equipment, such as Unihedron's Sky Quality Meter and Knightware's SQM Reader Pro are being used in a surprising number of studies worldwide. Some examples include:
- University of Hong Kong
- Governments of Australia, Italy, Spain and the Netherlands
- US National Parks Service
While astronomers have used light pollution studies for years to plan the locations of their observatories, many other issues are being studied now. The leading issues being studied are economic waste, harm to animals, and the inability to view the natural night sky. One of the most surprising issues studied recently was the effect of light pollution on urban air chemistry; that is, air pollution. This one was conducted by the National Oceanic and Atmospheric Administration and the University of Colorado.
Light pollution affects more than most people realize, and the list of problems caused by it is growing. Researchers will continue to explore this issue, and concerned citizens can take effective action today to mitigate the problem.
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