Saturday, September 26, 2009

When you wish upon a star

Welcome. This week has been characterised by some fairly average weather. Those of you tuning into Australia's premier football event around the world this afternoon will see plenty of our famous Melbourne weather on show.

Weather can have an impact on an observing campaign, so there have been some challenges in obtaining some of the data I have been chasing this week. I am getting great positive feedback on the blog - largely because I am blogging on my observations.

So this week, given the weather, I thought it would be good to talk about observation campaigns. This week I have barely jagged a couple of short sessions on
V4743 SGR and some of the surrounding variables in the same field. V4743 Sgr is also referred to as Nova Sgr 2002c making it an object of some interest, given its nova outburst in 2002. Over 200 observers have contributed to the AAVSOs lightcurve.

So what is it that makes an object "interesting"? Clearly a Nova outburst is something that is interesting, as professional astronomers are quick to follow up with highly accurate spectroscopy. The advantage of having amateurs "on their toes" and participating in regular campaigns is that professional astronomers can't afford to have billion dollar telescopes pointed at stars, waiting for years, for something to happen. (The hubble deep field shot is a noteable exception...but a deliberate experiment to look at nothing to see if something WAS there)

A good example of leveraging the skills of amateur astronomers is my data here on QU Sgr. This is a Mira variable star of little or no interest to anyone.....but who knows one day it may be significant or do something. If that ever happened, what would we have to compare it with? So whilst gathering some data on V4743 with my set up which has a fairly large field of view, it is important to grab a couple of readings on any other Variables in the field, as other observers are unlikely to ever go specifically to QU Sgr to collect data.

There are a plethora of variable stars requiring regular observations and a limited number of observers. Today we have the fantastic use of social networking, blogs, forums and membership of organisations such as AAVSO. In this environment connected communities of dedicated amateurs have organised campaigns based on a prioritised list of "interesting objects".

Rod Stubbing who discovered this months outburst of VX For was working through a carefully targeted list of variables that were "in season" ie at an optimal position in the sky for observing. Rod indicated to me it was his first observing session on VX For for the year. So you never know what you will find, and how many other people who are observing.

So I leave you this week with the completely insignificant Mira Variable QU Sgr that noone else has reported on for over 4000 days.

Wednesday, September 16, 2009

VX For Dwarf Nova Outburst .....update#2

The variable Star community is alive with excitement after Rod Stubbing an amateur astromomer from Victoria Australia discovered VX For in outburst for the first time since 1990.

After a 19 year spell the Dwarf Nova has moved into outburst. Importantly Rod appears to have caught it before its previous peak of 12.5 in 1990.

I was able to get some photometery on VX For and reported confirming data on Rod's exciting find to the AAVSO.

Mike Simonsen has written an excellent blog on this star with some of the history and the significance of the event. I imagine professional astronomers will be keen to get some spectroscopy on this interesting star in over the next month.

My observations were just a short run last night as the window is fairly tight from about 11:30Pm local time through to about 4:30am. The co-ordinates also restrict viewing to southern observers: RA 03:26:46.9 Dec -34:26:37.0 so our northern friends will have to leverage any access they can get to southern hemiphere scope......its called teamwork! Also Joe at the Center for Backyard Astrophysics is following the story with interest and rallying the troops!

Anyway it promises to be an exciting time as VX For entertains us for the coming weeks. My first light curve showed it right on the 13.0 magnitude observed the previous night by Rod Stubbing. Amateur Observers can post their results to the AAVSO.

Enjoy! I will post any further updates, you can also follow the light curve here as it develops.

Vx For Dwarf Nova outburst

Great work last night Rod. I jumped on it as soon as it came over the side of the shed and have it in the first image at an average of 12.951 M across the first three images I have downloaded (airmass of 1.5)

I should be able to tighten that up a bit when I process the rest of the run.

Data from my first image....

VX For 12.951 SNR 103

126 12.555 SNR 137
137 13.652 SNR 59

More later....

Firrst three images down:

#SOFTWARE=Photometrica 3.0
VX For,2455090.09733,12.936,0.011,V,NO,ABS,ENSEMBLE,na,137,13.660,1.55703,na,090915,na
VX For,2455090.09994,12.959,0.010,V,NO,ABS,ENSEMBLE,na,137,13.665,1.53358,na,090915,na
VX For,2455090.10256,12.991,0.011,V,NO,ABS,ENSEMBLE,na,137,13.662,1.51102,na,090915,na

Looks like Rod has bagged a beauty!!!!


Sunday, September 13, 2009

HD Video of M17

The array of desktop tools available to the home user today is nothing short of amazing. HD Video editing packages, access to media sharing sites like Youtube and social networks, and a market place of over a billion people.

The notion from the 60's of Governments allocating Radio and TV broadcasting licences seems positively ridiculous, compared to today's media rich world.

Anyway, my little contribution for today - A short HD Video tour of the M17 Nebula, following up my earlier post this week.

Of course one of the little quirks of Newtonian astrographs is they view everything upside down. So for those of you still looking for the Swan....try this way up! However my son said "thats not a swan thats a Dingo"! (if the white bit is the gnarling teeth and the black patch the nose then.....ah....yep....there's a dingo in there too, perhaps even a crocodile!!!! Maybe why this fine emission nebula has more than one name.


Saturday, September 12, 2009

Connected Astronomy

I really enjoyed Fraser and Dr Pamela's AstonomyCast Podcast last week about "Next Level Telescopes" [Episode #150]. It was a fantastic roadmap of information, so I thought I would follow up, and build on that, by doing a little tour video of my own setup.

The advantages of remote, connected astronomy are many:

-No setup and tear down time
-No cold night air on the back of the neck
-No travel to dark sites
-Desktop convenience
-Collaboration, community and access to other highly skilled experts

Disadvantages (opportunities for personal growth)are:
-Its highly technical and very complex
-Can be expensive to do it yourself
-Broadband access can be challenging in remote areas
-WARNING - check you telco's broadband download limits on your Internet Plan

Whilst some of these interfaces are customised/proprietry the bulk of the legwork is done by Maxim DL, TheSky, FocusMax and the telescope controller.

Of course most challeneges can be overcome if you are dealing with people who know what they are doing, and you are prepared to be patient. There is nothing better than setting up a run and then relaxing in the leather recliner with the iPhone in the cup holder as a virtual console to monitor the progress of the run. Even better is setting up an image run in the dead of night whilst you are fast asleep, and downloading the images next day.

Here is my latest Astrophotography image: M17 or the Omega Nebula is not as often photographed as some, but the surrounding star field makes it a lovely composition.

This LRGB photo totaling 90 mins of imaging time 960sLum, 1500sRed, 1500sGreen, 1500sBlue binned 1x1 shows what is achievable.

So with the last word (or should that be letter) on connected astronomy..... ;-)......Enjoy!

Friday, September 4, 2009

Variable by Nature

Variable star photometery is a key area where amateur astronomers make a significant contribution to Science.

The American Association of Variable Star Observers AAVSO has a large membership of skilled amateurs, great resources, extensive observation records and a great system for marshalling the variable star observers in the objective of creating light curve "memory" for others to build research upon.

Only this week an alert went out to the membership asking for urgent observations on variable star V2105 OPH. Dr Brian Espey from Trinity College Dublin, is anxiously awaiting a window on the Hubble Space Telescope to perform Ultraviolet Spectroscopy.

CCD cameras gather light based on their ADU count and the Quantum Efficiency of the Camera. In order to do accurate photometery you need to carefully select the durationof your exposures to make sure you don't saturate the star, as this destroys the Signal to noise ratio and distorts the ADU count. I don't have any experience in Spectroscopy but I imagine you would have to be just as careful. That's why if you are fortunate enough to be using the probably don't want any surprises. An appeal to the amateur community therefore becomes essential to help the Scientist prepare for their observation session appropriately.

Variable star observers range from people with good eyesight and a knowledge of the nearby stars (derived from AAVSO's excellent maps and records) through to binocular observers and others with more powerful telescopes, CCD cameras, PEP devices and sophisticated software packages. The process involves determining the Magnitude of a star by comparing its brightness with nearby stars of a known magnitude. Observers then report this magnitude and the data is added to the database for that star.

Dr Espey was able to receive 7 observations with in the first 36 hours by keen amateurs and members of the AAVSO.

Once you gain the basic skills, you can further your skills with increasingy sophisticated tools.

Why do we do it?

Good question, for me the satisfaction of making a measurement and putting it into the database and having someone else on the other side of the world make the same observation and record the same measurement to a high degree of accuracy and precision is amazing and very satisfying. In science it is important to measure accurately, but the ultimate test is having results confirmed by others - ie reproducable data.

Here are some of the recent observations and the tool photometrica that I use to process my results.

The AAVSO report follows a set format (Abreviated below) and contains the measured magnitude and the magnitudes of nearby Check and Comparison stars as well.

TY Sgr,2455049.90881,9.626,0.002,V,NO,ABS,ENSEMBLE,na,CD-24 15162,10.414,1.33521,na,090825

A tool such as Photometrica can help you process and format the data, if you are plotting your own light curves.

So join the AAVSO today, learn some new skills, and do some real science!!!


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