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Richie's Blog


Photographing an Iridium Flare
Written by Richie Jarvis   
Friday, 01 August 2014 15:50

Last night, I was taking 2 minute exposures of the constellation of Cygnus the Swan from my observatory.  This morning when I went through the exposures, I discovered I had caught something in one of the exposures.  It didn't look like a meteor, as it appeared to rise and fall in brightness over a period of time, whereas a meteor I would expect to start off dim and get brighter and then vanish.  My suspicion was that it was a satellite - specifically one of the Iridium group of satellites.

The Iridium satellites are used for satellite phone calls.  They are named because it was originally intended to launch 77 satellites providing call coverage around the globe.  However, it was determined that all 77 satellites were not needed to provide full worldwide coverage, so there are currently 66 operating satellites in orbit, with 6 spares in a holding orbit. The orbital height of the operational satellites is 485 miles on average.  They are travelling at 16,832 miles per hour, and complete one orbit of the Earth every 100 minutes.

The reason for the flare seen in the picture is that these satellites have 3 door-sized antennas angled at 40 degrees away from the main body of the satellite itself.  They are arranged equally, with 120 degrees between them.  When the light from our Sun hits the antenna, about 4-5 times a day the reflected light create a 6.2 mile wide circle of light on the surface of the Earth.  To an observer, this appears as a bright flash of light which suddenly gets brighter, then dimmer as the satellite moves over their head.  The date and time of each flash is easily predictable, as the orbit and attitude of the satellite is known precisely.

To find out whether I had accidentally caught an Iridium flare, and check which satellite and antenna  my camera saw the reflection from, I checked on http://www.heavens-above.com, which provides detailed prediction for most satellites circling the Earth, including the International Space Station and Iridium Flares.

I was able to determine exactly which satellite I had captured - Iridium 72 - and the reflection was from the front facing antenna (its direction of travel).  At the time of the flash, the satellite was 640 miles away.

Here is the track of the satellite from Heavens-Above.com showing the predicted position of the flare:

I PDF'd a version of the Flare information from Heavens-Above.com, which you can download here.

Attachments:
FileDescriptionFile size
Download this file (2014-08-01-010147-Iridium72-FlareDetails.pdf)2014-08-01-010147-Iridium72-FlareDetails.pdf 598 Kb
 
Work in Progress - Veil Nebula Mosaic
Written by Richie Jarvis   
Saturday, 19 July 2014 15:22

I've taken many pictures of parts of the Veil Nebula over the years - you can see them in my Galley.  Back in the days when the New General Catalogue was compiled (thats where the NGC designation comes from), the parts of the Veil Nebula were given separate designations.

This year, I decided to see if I could take a picture of the whole of the Veil Nebula.  My camera (SXVR-H18) and telescope (101mm @ F/7) combination can only see 1.4 x 1.1 degrees at F/5.6 with my Televue Focal Reducer, so to get the complete veil requires taking images of different areas of the sky, and stitching them together.  You can see the boundaries of the panes in the image above.  Each 'pane' is the result of stacking many images together.  So far there are 97 images making up this mosaic.  So far, I have been concentrating on the Hydrogen emission wavelength with my Ha narrowband filter.

This will be a several year project, as I then need to shoot with an Oiii (Oxygen) filter, and then choose whether to shoot with an Hb (Hydrogen Beta) or Sii (Sulphur).  I might even be able to incorporate some of the data from previous imaging runs - time will tell.  I have some gaps to fill in the Ha band - I just need some clear nights!

Here are some of the other pictures I hope to incorporate should the inclination take me:

NGC6992/NGC6995/IC1340 is known as the Eastern Veil, or Network Nebula
NGC6992 is the bright area, NGC6995 is the 'rectangle' element of the Eastern Veil Nebula.  Between the Eastern and Western Veil, Pickerings Wisp is the fainter triangle shaped structure
NGC6960 is known as the Western Veil, Witches Broom, Finger of God, of Filamentry Nebula

At a distance of 1,470 light years away, the Veil Nebula is the result of a supernova which is thought to have exploded 5,000 to 8,000 years ago.  The resulting gas and dust released spread out into this 3 degree area of sky (roughly 6 times the diameter of a full moon) in the time since the explosion.  It is one of the largest, brightest features in the X-ray band.  The dust and gas is estimated to be travelling at the huge speed of 370,000 miles per hour away from the original star which spawned it.

Read more about the Veil Nebula and see a beautiful picture from the Hubble Space Telescope here: http://www.space.com/4136-veil-nebula-pierced-hubble-gaze.html


 
2014-01-22 - Supernova in Galaxy Messier 82
Written by Richie Jarvis   
Wednesday, 22 January 2014 21:14

This morning, I saw an interesting email come into my inbox.  It reads as follows:

Subject: [vsnet-alert 16812] Re: PSN J09554214+6940260: bright (11.7 mag) supernova in M82
At UT 2014 Jan 22.305, we obtained a spectrum of PSN_J09554214+6940260 (discoverer: S. J. Fossey) with the Dual Imaging Spectrograph on the ARC 3.5m telescope. We classify this as a Type Ia supernova with a Si II velocity of 20000 km/s. The best superfit match is SN2002bo at -14d. The supernova has a red continuum and deep Na D absorption.

A type 1a supernova is what happens when a binary star system starts to tear itself apart.  In essence, a very small dense white dwarf rips the material from the surface of its neighbouring star.  It appears to be relatively common when one of the stars in a binary star system inflates when it becomes a red giant.  The surface of the red giant is now much closer to the companion star, and so matter starts to transfer from the red giant to the smaller star.  As the smaller star accepts matter from the giant, the system becomes unstable, and the small white dwarf explodes violently.

The velocity quoted above shows that the shockwave of this star exploding is travelling at 20,000 km/s - thats almost 12,500 miles per second - pretty quick.

Type 1a supernovae are special because they allow astronomers to accurately gauge the distance from the Earth of the galaxy that spawned it.  Each one that is identified gives astronomers much more accurate data about the Universe around us.

I managed to gather a quick snap of Messier 82 tonight before the clouds rolled in.  This animation shows the difference between some Messier 82 images I took last year in February versus the 2 exposures I managed to capture tonight.

 

 
Nova in Delphinus
Written by Richie Jarvis   
Thursday, 22 August 2013 23:01

Discovered by Amateur Astronomer Koichi Itagaki of Yamagata, Japan on the 14th August, here is my picture of the Nova along with the Planetary Nebula NGC6905, which itself the result of a Supernova in the past.

You can use the picture featured on APOD to find it for yourself - it is still very bright in the sky!

Here is my picture - with a text overlay.  See the full-sized version in my gallery here

 
Running Your Own Astronomy in the Pub
Written by Richie Jarvis   
Friday, 31 August 2012 17:13

 

So you want to run your own Astronomy in the Pub event?  GREAT!

I run my events at my local pub, The Horns Lodge in South Chailey.  So far, I have run 2 events, one to coincide with BBC Stargazing Live in February 2012, and one in August 2012.  Both events were very well received, and we were lucky to have clear skies on both occasions.

 

 

What do you need to get started?

  • Some Amateur Astronomer volunteers
  • A dark site Pub with a willing publican
  • Some Speakers
  • Some Telescopes of different types/costs/aperatures
  • A projector/large television to show your Speakers presentations on
  • A laptop to show your Speakers presentations on
  • A projector/large television to show a Sky Chart on
  • A laptop to run Stellarium (or other suitably pretty Sky Chart on)
  • A Public Address System

What does your Publican get out of it?

Lots of people in their pub!  Our first event attracted approximately 350 people.  Our second event attracted about 120 people.  The pub did a roaring trade for food and drinks both times, so it is well worth the investment of time and money from the publicans point of view.

How much will it cost your Publican?

It depends on how extravagant you want to be.  If your publican is prepared to fund speakers, and provide free drinks for volunteers, then great!  In my events so far, the publican has provided free drinks and some food for the volunteers.  You might want to agree with your publican beforehand a certain number of drinks per volunteer, and how the volunteers can be identified!

How much will it cost me?

The aim of these events is to put on a free public event to promote Stargazing in your local area.  The only costs you should incur are some printing costs, and some time.  You should ask your publican to cover travel and speaker costs - its them making the money after all, not you!

 

When should I schedule an Astronomy in the Pub event?

Obviously, the best time will be during the BBC Stargazing Live period, when the BBC are promoting events across the country.  The BBC also run a series of television programmes around the same time which help stimulate the public interest in Astronomy.

You should also try to pick a date when the Moon is up, there is an International Space Station pass or Iridium flare, and ideally at least one bright planet.  You want to aim for targets which make the public go 'Wow!'.  Use CalSky in order to find out when is a good time for your location.

Printing for an Astronomy in the Pub event

  • Event Itinerary and Notes
    • A small leaflet detailing Lecture times and any events which are timed (such as when an object is visible, such as an ISS pass)
    • Remember to make sure that the leaflet instructs the public to be careful around telescopes, and cautions about Solar Observing
  • Volunteer Itinerary and Notes
    • Get a times list from calsky
    • Add any notes about rules for volunteers if appropriate
  • Information Sheets
    • I have produced a series of information sheets which I laminate and place around my pub.  You could do the same as well.

How many volunteers do I need?

You will need at least one willing volunteer per telescope onsite, preferably more to allow for volunteers to take a break and enjoy the event themselves.  A manned telescope will probably attract a queue, so make sure you get someone to take drinks orders directly to your volunteers!

What if its Cloudy/Wet?

Find an area to setup some different size and type of telescopes under cover.  Make sure that at least one knowledgeable person is on hand to explain about the telescopes to the public.  If you want, you can also run a Sky Chart to show what users would have seen if it was not cloudy.

What sort of talks should I have?

Its up to you!  Bear in mind that your audience is going to be non-astronomers though, so keep it simply.  You might want to have some talks aimed at Children earlier on in the event as well.

How do I advertise the event?

  • Publish your event on the BBC Things to Do Website
  • Contact your local radio station about the event
  • Contact your local paper about the event
  • Contact your local STEM group about the event - they will let local schools know
  • Invite the press to create an interest in future Astronomy in the Pub events

 

Don't Forget!

Enjoy your own event!  This is a hobby - if you don't enjoy promoting Astronomy, then why are you doing it?

Startrails_id8317to8339

Star Trails by Dr Darren Baskill - more images available on his photostream @ Flickr.com

 
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