Making a solar filter

With a solar eclipse coming up on 20th March 2015 I’ve finally got round to making a solar filter for my 72mm refractor. I’d looked at purchasing one but one of the right size was never in stock.  I wanted something sturdy rather than made of card and I hit upon the idea of using a CD/DVD “cake” as the main body (with a large enough hole cut in the top) and sandwiching some solar film between two rings cut from the protective discs you get at the bottom of the “cake”.  I also made a pair of filters for my binoculars out of cardboard (cereal carton).  This first image shows the body of the “cake” with a hole already cut into it, and the two protective discs. Also seen are a 12″ steel ruler, radius cutter, pair of compasses, caliper, solar film (in envelope under ruler) and “invisible” photograph mounts (which are used to attach the rings to the film)

A 15mm diameter hole (the size of the central hole in the discs) was drawn on an off-cut of fibreboard (ply would have been better) and one of the discs positioned over it and fixed in place with screws. The radius cutter was set to a radius 10mm less than that of the discs and its pinpoint located in the same hole created by the compasses

Here we see both rings completed:

Photo mounts are attached around each ring:

A square of solar film is cut just larger than the rings and, having removed the backing paper from the adhesive mounts, the film is carefully sandwiched between the rings:

The rings are then fixed in place inside the modified cake, and here’s the finished article after the main body has been painted (prior to the filter being added!):

Filter attached to telescope ready to image the eclipse:

A cropped image taken using the above:

Accurately setting the “Home” or “Park” position on a Skywatcher EQ5 Pro Mount

Update 18 Jun 2011:

Since I originally prepared this article I’ve found that the steps set out in the Starting from a known position section aren’t necessary.  When the mount is powered on, regardless of whether you choose to start from parked position or not, and irrespective of what position the axes are in,  the positions of AX1 and AX2 shown in UTILITY → SHOW POSITION will be the same.  I’ve therefore removed the steps that are no longer required

It’s been quite a while since my last posting.  In the intervening period I finally got round to acquiring a decent mount, the SkyWatcher EQ5 Pro. The only trouble is the weather’s not been too good andit’s way past 10pm before it gets dark enough for observing!

One element of setting up an equatorial mount is the establishment of the “Home” position. This is where the mount is “parked” at the end of a session. It is sometimes described as “weights down, scope up” and is often the position displayed in adverts. There’s an excellent video tutorial on YouTube accessible via http://www.astronomyshed.co.uk/ (“Complete Setup From A to Z Part 1”) which shows how to establish this position using an HEQ6 mount.

In essence, the procedure uses a spirit level to “level” an axis then rotate the axis by 90^o so that it is then perpendicular. When both the RA and DEC axes have been set this way, the mount is in the correct Home position.

As owners of Skywatcher EQ5 mounts have long accepted, the setting circles leave a lot to be desired, and while it’s possible to use the technique in the tutorial on an EQ5, the inaccuracy of the setting circles means it’s a bit of a hit and miss affair.

The following procedure builds on the technique, using the Show Postition function of the SynScan controller to accurately determine when an axis has rotated through 90^o. Though described for an EQ5 mount, this procedure can be used with any equatorial mount with SynScan, whether factory-fitted or upgraded.

On the EQ5 tripod, one leg is marked N. This is the leg which is pointed North. For the purpose of this procedure this will be regarded as the front of the mount.

It is assumed that the user is familiar with the operation of the SynScan controller and its menus. Navigation to a sub-menu will be described thus:

UTILITY → SHOW POSITION

( Starting from a known position section removed)

Setting the RA axis

1. Stand behind the mount, release the RA clutch and rotate the RA axis until the weight bar is horizontal and to the left. Use a spirit level to check then lock the RA clutch.
2. Switch ON
3. Step through the setup procedure. Note: Setting date/time/location correctly is not required at this, or any other stage of the process, nor is 1,2 or 3-star alignment.
4. Show the position of the axes.     UTILITY → SHOW POSITION
5. Use the scroll keys to change the display so that the axis positions are shown in degrees, minutes, seconds:

AX1=+090^o 00′ 00”

AX2=+000^o 00′ 00”

(AX1 is the DEC axis, AX2 is the RA axis)

6. Set a fairly high slew rate (RATE 8 for example) then use the RA directional key to slew the mount until AX2 is close to reading 90^o. Select a slower rate and carefully slew until the display reads

AX1=+090^o 00′ 00”

AX2=+090^o 00′ 00”

7. Using a fine marker and straight edge, make a mark to enable you to manually return the RA axis to its parked position.

Setting the DEC Axis

1. If you have one, fit a dovetail bar to the puck. This will provide a straight edge to rest the spirit level on.
2. Release the DEC clutch and rotate the DEC axis until the dovetail is horizontal, using the spirit level to check.
3. Again, start off with a high slew rate and rotate the DEC axis until the display indicates the AX1 axis is 90 degrees different to what it was. If your preference is to have the DEC motor to the left, then the display should read

AX1=+180^o 00′ 00”

AX2=+090^o 00′ 00”

If, however, you prefer to have the DEC motor on the right, the display will read

AX1=+000^o 00′ 00”

AX2=+090^o 00′ 00”

8. Using the marker and straight edge make a mark so the DEC axis can be returned to this position manually
9. Switch OFF
10. Switch back on again and step through setup.
11. Choose UTILITY → PARK SCOPE then switch off when prompted

The mount now has its axes accurately positioned and parked.

I Feel a Great Disturbance…

I’m still shocked by the events of Friday night, just as I was 41 years ago when it transpired that the muffled “thuds” I’d heard 3 miles or so away on 21st November 1974 were, in fact, the sound of the bombs in the Mulberry Bush and the Tavern in The Town in Birmingham.

The terrorists of Paris, Beirut, Syria, Afghanistan, Jodan, Gaza, West Bank, Israel are no more representative of Islam, Christianity or Judaism than the IRA bombers were of the Irish, or Catholics, or the UDA/UDF were of Protestants.

How do we deal with the fanatics? The insane cowards who hide their acts behind the religious beliefs of millions? Not by bombing, that’s for sure, as it only swells the ranks of those warped individuals who believe that slaughtering fellow humans will somehow raise them to greatness in the eyes of their deity.

Jeremy Corbyn’s views on the killing of Bin Laden or “Jihadi John” have been taken out of context deliberately by the media. Anyone who really truly cares about freedom and justice will see the problem: How can we in the West expect others to adopt our systems of justice and democracy when it’s so easy to sweep away the process of law in order to exact revenge, to “do what needs to be done.” Rather than seek to flex their muscles and show how good they are at “taking out” the likes of Bin Laden and Emwazi, the UK and US forces should concentrate on capture, extraction and trial.

There are those in government who will seek to use these atrocities to further erode our freedoms “for national security.” If they do so, then the terrorists can claim another victory. It’s their intention to undermine our way of life because it doesn’t fit with their distorted, misogynistic view of the world.

Those suspected of Friday night’s horrors must be captured and brought to book, rather than made martyrs of.

Without wishing to appear glib or flippant, when I heard the news of what happened in Paris, this sprang to mind:

DTB or not DTB… Part II

Well it’s taken me a lot longer to post this than I’d originally intended. Partly because of time (or, rather, lack of it) and partly because since my last posting on this topic I’ve re-installed Linux on the laptop and had forgotten most of what I did previously! Fortunately I’d taken a backup of things!

(edit 2 may 2014: Even longer than when I first started writing this part as I’ve been through a number of changes in Linux since!)

In part 1 I said how the files for a recording are held in a directory (“folder” in Windows parlance) such as

~dvr2010090102353301.rec

Within this directory are a number of files with the suffix .trp These files need to be combined.  To do this I use a piece of software called ProjectX available from Sourceforge here:

http://project-x.sourceforge.net/

Though ProjectX can combine the files into a single video file, I found that the audio and video were out of sync.  The solution I found was to select and option in ProjectX to aplit the audio and video components then use the mplex command in Linux to re-multiplex them into a single file. For Ubuntu/Mint (and probably Debian) mplex is part of the mjpegtools package which is installed with the command

sudo apt-get install mjpegtools

Stage I – ProjectX

After the ProjectX ZIP file has been downloaded, unzip it then cd into the directory:

cd Project-X_0.91.0

Then start the program with the following command:

java -jar ProjectX.jar

You then need to load all the .trp files.  The following image shows the icon to select (arrowed). A file picker pops up from where you select the required files.

ProjectX file picker

 

 

 

 

 

 

 

 

Once the files have been selected, make sure you specify a suitable location for Output directory then click on prepare >> and select de-mux:

ProjectX Process window

 

 

 

 

 

 

 

 

Finally, click on the green arrow to start the process.  You may get some warnings appear but I’ve found they can usually be ignored.

In the output directory you will find a number of files, for example:

dvr2010111020022501.rec00_log.txt
dvr2010111020022501.rec00.sup
dvr2010111020022501.rec00.sup.IFO
dvr2010111020022501.rec00.mp2

The next task is to use mplex to create a .MPG file which will have the video and audio in synch:

mplex -f 8 dvr2010111020022501.rec00.mp2 dvr2010111020022501.rec00.m2v -o MyProg.mpg

The resultant .MPG file can then be played or, if desired, written to DVD using DVDStyler but that, as they say, is another story!

 

 

 

 

Reflections

I read yesterday of the passing of the last remaining RAF pilot who fought in the Battle of Britain.  We’re coming up to that time of year when we take a moment to remember those who go to war on our behalf and who pay the ultimate price.  Through their deeds we currently enjoy certain freedoms that others seek to curtail because they don’t fit in with their political/racial/religious agendas.  Each seek to control, in one way or another, the lives of others, to make everyone else conform. Each pays lip service to “tolerance” but can be deeply intolerant of others’ views. Sadly, this is why humanity has seen so many conflicts, small and large.

Each year we hold services of remembrance, vowing never to forget the sacrifices made by those who’ve died in conflict, yet hardly a day goes by without us hearing of lives lost.  We do those people (military and civilian) a disservice by continuing to try to impose our will on others.  Maybe, one day, our species will wake up to itself and accept its diversity. Maybe then we can move forward.

When I started this post I intended calling it “An early ode” but, as can sometimes be the case with me, I got side-tracked 🙂  Here is the real reason for the post:

 

At age 14 you went to war,
Saw sights you’d never seen before,
You dared to go where no boy should
And did the very best you could
So young you were, and yet so brave
And in the end your life you gave
But do not feel you gave in vain
Whene’er the world’s at war again,
For years ahead, in each November,
Tears are shed, as we remember,
Silently, for minutes numbering 2
We stand, reflecting, thanking…
You

 

The value of preparation (and what happens when there’s a lack of it!)

A tale of expectation, apparent disaster, elation, more expectation, annoyance, disappointment…

Saturday

(expectation)

Evening was looking promising for so astronomy/astrophotography, so once it was dark enough for me to see Vega, Deneb, Altair and Polaris with the naked eye I started setting up.  I spent about 30 mins getting the tripod level and pointing North then attached EQ5 mount and got that polar aligned.  For some bizarre reason I’d decided not to extend the tripod legs, so kneeling down to peer through the polarscope made the old knees creak a bit. Anyway, I digress. Once the mount was aligned, I hooked up the controls and connected to my 88Ah leisure battery.  I then attached the telescope to the mount, fitted a 20mm eyepiece, removed the end cap from the ‘scope and was ready to go…or so I thought!

(apparent disaster)

I switched on and went through the setup procedure then decided to use Caph (for those of you who don’t know, Caph is the top right hand star in the W of Cassiopeia) hit Enter and…horrible screeching sound accompanied by the scope moving in the wrong direction!  Pressed ESC to stop the movement and checked that I hadn’t got cables mixed up (unlikely as I normally leave them connected when the mount’s not in use).  Nope, cables OK so try moving the mount with the direction keys. Movement OK in Right Ascention (RA) but attempts to move in Declination (DEC) produce the screeching noise.   Time to do a bit of fault finding…

• Removed cover from DEC motor and tried movement…SCREECH
• Remove motor from mount and try movement…SCREECH
• Remove transfer gears and try…no SCREECH but motor shaft oscillating back and forth.
• As RA movement was OK I then connected the cable from the motor control box (which normally connects to RA IN on the mount) to the motor and tried the RA keys….Motor works fine!
• Reconnect the cables in their normal positions and try DEC movement…oscillating motor.

Time to think… What was different compared to when the mount was last used about 10 days previously?  The only difference I could think of was that I hadn’t put the MC box and Hand Controller back in the large plastic box they’re usually kept in with a bag of silica gel.  Could a bit of dampness have crept in and affected the circuitry (it having been quite humid)?  Possibly.  Anyway, nothing for it but to pack up for the night and take a look on Sunday..

Sunday (afternoon)

(elation)

Got the MC box and Hand Controller out of their box and connected everything up.  Applied power, went through setup and tried movement….

and…..

IT WORKED!

Huge sigh of relief as I’d had visions of going through a process of elimination and possibly having to return the mount to retailer.  I can only assume that damp had somehow played a part.  My elation was tempered somewhat when I checked the weather app on my phone and it indicated it’d be a cloudy night 😦

(more expectation)

Kept a watchful eye on the sky and by 9pm it was looking good, so off I go again…

I double check that mount is working OK before taking it outside…Yes, so set up everything as before.  Apply power and go through setup no problem.  Select Caph as alignment star and the mount slews in the right direction. Now, I normally expect the first alignment to be off-target unless I’ve got very good polar alignment.  The trouble is, although Caph is a bright enough star, when looking through the telescope with the 20mm eyepiece I don’t have a wide field of view, so the alignment doesn’t have to be off by much for the target star to not be in view.  After I spent a few minutes trying to find Caph I decided to try for Vega on account of it being so bright and easier to find.  Finally got Vega in the centre of view then went back to Caph, which appeared almost dead centre in the field of view.  A few minor adjustments then time to get everything else set up: finder/guider (a webcam attached to a finderscope), DSLR and laptop.

(annoyance)

This was the first time I’d used the laptop with mount etc. since re-configuring it earlier in the week.  I thought I’d re-installed all drivers and software but it turned out I hadn’t.  First off the webcam wasn’t recognised so I ended up installing the driver for the camera again (on reflection I may have tried installing the wrong driver previously).  Loaded up PHD (guiding software available from  http://www.stark-labs.com/phdguiding.html) and selected the camera. No error this time and I could see some stars in the image.  I then tried getting PHD to select “EQMOD ASCOM EQ5/6” from the ASCOM telescope chooser but whenever I did so, the OK button was greyed out.  Re-installed ASCOM and tried again.  Eventually got it to work.  Next up the DSLR.  Connected the USB cable and tried opening EOS Utility – camera not found.  Try Backyard EOS – same result.  Change cable to the one supplied with the camera , SUCCESS!  I’m sure I’ve  used the other cable before now without a problem but it did only cost £1 so I shouldn’t expect too much!  Finally I’m ready to go…

Webcam working?  Check
DSLR switched on?  Check
Software running? Check

Right, just need to get focus sorted out…

(disappointment)

Put bahtinov mask on front of scope and looked at Backyard EOS.  Select Frame & Focus…nothing on screen.  “That’s odd.  I should at least see something” Then I look up….complete cloud cover!  I’d spent so much time resolving issues with software/hardware setup I hadn’t paid attention to the sky which obviously had other ideas!  So that was a second night ruined.  Time to pack up and wait for the next clear night (whenever that might be).

Epilogue

All of the above just goes to show how important preparation can be.  Having re-installed the laptop I should’ve taken time (in daylight) to check out all the components.  That way I’d have been able to at least get some images.  The events of Saturday night have shown me (assuming that damp/moisture/humidity was the cause) the importance of taking care of the equipment.  There’s still room for improvement and there are probably ways I can make things easier by adopting a set routine.  Though not mentioned above, my initial photographic target was the ISS as that was due over at 22:09, so once the mount was set up I attached a Vanguard ball head to a small dovetail bar and attached it to the mount then attached the DSLR.  Unfortunately, next door’s conservatory was lit up and causing me problems so I spent time positioning the camera to minimise the effects of light cast.  Time of ISS pass was fast approaching so I set the camera to continuous mode shooting, ISO1600, wide aperture, 10s and waited.  Checked app on phone which showed the pass had started, so I went down the garden to look out for it (garden faces roughly ENE).  Eventually it appeared.  Unfortunately, had I checked the path the ISS was going to take I would’ve found out that, from where I was set up, the pass would be completely obscured by my house and next door’s house.  Had I noticed that I’d have set the camera up on my camera tripod further down the garden – preparation again!

DTB or not DTB, that is the question…

(or how a tale of woe was reversed)…

About 5 years ago, when the old VCR gave up the ghost, I purchased a Wharfedale 160GB PVR with twin tuner.  I guess at the time I’d had it in mind at some stage in the future to acquire a DVD recorder so I could off-load programmes from the PVR to it. At least that was the plan!

Throughout the years since then I’d wondered a couple of things:

1. What could be done with the DB9 serial connection on the back
2. What sort of hard drive was inside and, more importantly, would I be able to read it on a computer?

I never got round to doing anything about 1, but events this week have forced me to address 2 – I returned home on Monday to find the PVR dead! 😦  Having done the usual things (unplug, plug in, change fuse) I decided to take a look inside:

Inside my (now dead) Wharfedale PVR.

Is this an IDE I see before me?  Well as it turns out, yes.  A 160GB Western Digital hard drive.  “Simples,” thinks I. “Just have to pop it in my Lacie external USB drive case and Bob’s your mother’s brother!”

Well….not quite!

HDD was removed from the PVR and installed in USB case and connected to laptop running Linux Mint 12.  a quick fdisk revealed:

Disk /dev/sdf: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xcfaab5fa
 
Device     Boot  Start       End     Blocks Id System
/dev/sdf1           63    417689    208813+ 83 Linux
/dev/sdf2       417690 312576704 156079507+ 83 Linux

So far, so good. It looks like the embedded O/S was Linux-based.  Wonder what filesystem types were used:

/dev/sdf1: UUID="7fc78ac0-b003-9dc0-cc66-e0c1a4e0cbc1" TYPE="ext2" 
/dev/sdf2: UUID="7fc78ac0-b003-9dc0-cc66-e0c1a4e0cbc1" TYPE="ext2"

Looks OK apart from both partitions having the same UUID Ever get the feeling things are too easy sometimes?  Read on….

# mount /dev/sdf1 /mnt
# df -h /mnt
Filesystem    Size Used Avail Use% Mounted on
/dev/sdf1     204M 6.4M  198M   4% /mnt

OK. So the first partition mounts.  let’s try the second…

# umount /mnt
# mount /dev/sdf2 /mnt
mount: wrong fs type, bad option, bad superblock on /dev/sdf2,
 missing codepage or helper program, or other error
 In some cases useful info is found in syslog - try
 dmesg | tail or so

ARRGH!  Do I run fsck and try and repair superblocks (risking  corrupting what’s on there)? Best to exercise a bit of caution at this stage, so I used a utility called partimage to take a backup of the second partition, writing to a 500Gb USB drive I have.  Partimage works at a lowere level than the filesystem and will create an exact image of the partition, split into 2Gb files if required, thus enabling the recovery of the partition should something go wrong.

Whilst partimage was doing its thing, considerable Googling was done, with the upshot being that the second partition was formatted using a “modified” ext2 using 32K blocks rather than the usual (maximum) 4K blocks. Other PVR users had attempted the same thing and hit the same problem (it turns out that the Wharfedale unit is really made by Vestel, who provide similar re-badged units to supermarkets etc).  Under normal circumstances, Linux can’t handle filesystems with 32K blocks (well, not without patching the kernel and I wasn’t about to start that).

What to do?  Well, loathe as I am to say it, this is where a piece of software written for Windows called ext2fsd comes in which basically adds a driver to Windows so that it can read ext2 filesystems. I installed the software and connected the drive and sure enough, the second partition and its contents were visible.  Each programme recorded is stored in a separate directory (folder in windows land) with the directory name based on date/time recorded. For example, here’s the directory holding the earliest recording:

~dvr2007081322003801.rec

“That’s odd.  I’m certain I didn’t get the PVR until September 2007” Looking at some of the other directory names it seems the month and day portions start at 00 (for the 1st), so the directory name breaks down thus:

2007                 Year
    08               Month (-1, so this in fact indicates September)
      13             Day (again -1, so this is 14th)
        22           Hour
          00         Minute
            38       Channel (In this case BBC4)
              01     All the recordings end in 01 for some reason

Coming up in Part II: Getting to grips with video encoding and producing a DVD…

Weathering the weather

Astronomy can be a frustrating pastime at times.  The typical British weather we’ve been having lately has been a PITA!  It’s either clear early evening when I’ve just got home from work and winding down with a spot of food, only to cloud over later at around the time I’d think of setting up, or it’s so cloudy at first I abandon any idea of setting up, only to find that by 10PM the sky’s crystal clear!

All the time that Orion’s been in a favourable position for me to image I’ve been unable to get everything sorted out.  I did manage to get a half-decent image of the nebula back in November but any plans of doing a mosaic of the region have been thwarted.  Maybe I’m being a little ambitious.

I may turn my attention over the coming months to more northerly targets (unless I can get some quality imaging time in at the dark site) though some may require considerable numbers of subs to create a decent image.

Today was looking promising, but the clouds have rolled in again, so I shall return to familiarising myself with EQMOD etc.

For the fallen

Tommy Atkins was a boy who answered Kitchener’s calling.
The gun he carried was no toy, nor were those brave men falling.

Tommy’s spirit still lives on today, as brave men go to war.
Some, the ultimate price do pay, as many did before

Now their eyes no more can see, their bodies lie there still.
Lives given that we may be free, to speak and think at will.

For all that you have done, we salute you Tommy Atkins.
At the setting of the Sun, we remember you Tommy Atkins.

A feast of ISS passes

We’ve recently been treated to some bright passes of the International Space Station and it looks as though there are more to come (weather permitting) over the next week or so.  The following table (edited from http://www.heavens-above.com ) shows the times of the brightest passes.  Times/directions will vary depending on where you are but should be fairly accurate for anyone in the Midlands:

Date	Mag	Starts			Max. altitude			Ends
		Time	Alt.	Az.	Time	Alt.	Az.	Time	Alt.	Az.
17 Jun	-3.6	23:16:59	10	W	23:20:11	76	SSE	23:23:17	10	E
18 Jun	-3.4	22:15:23	10	WSW	22:18:29	60	SSE	22:21:36	10	E
18 Jun	-3.6	23:51:06	10	W	23:54:15	78	S	23:57:25	10	E
19 Jun	-3.5	22:49:28	10	W	22:52:36	80	S	22:55:45	10	E
20 Jun	-3.4	21:47:51	10	WSW	21:50:59	70	SSE	21:54:07	10	E
20 Jun	-3.5	23:23:37	10	W	23:26:45	71	S	23:29:54	10	ESE
21 Jun	-3.5	22:22:01	10	W	22:25:09	80	S	22:28:18	10	E
21 Jun	-3	23:57:51	10	W	00:00:52	43	SSW	00:02:27	23	SE
22 Jun	-3.4	22:56:14	10	W	22:59:20	62	SSW	23:02:28	10	ESE
23 Jun	-3.4	21:54:39	10	W	21:57:47	77	S	22:00:56	10	E
23 Jun	-2.6	23:30:32	10	W	23:33:26	34	SSW	23:35:05	20	SSE
24 Jun	-3.2	22:28:54	10	W	22:31:59	52	SSW	22:35:03	10	ESE
25 Jun	-2.2	23:03:20	10	W	23:06:03	27	SSW	23:08:01	15	SSE
26 Jun	-2.8	22:01:41	10	W	22:04:41	42	SSW	22:07:41	10	SE

It’s nearly 54 years since Man’s first artificial satellite was put into orbit and 50 years since Yuri Gagarin first ventured into the unknown.  The first decade and a half of space exploration saw a flurry of activity on both sides of what was then known as the “Iron Curtain”, with the U.S.A. and U.S.S.R going head-to-head, each trying to out-do the other in demonstrating their technical prowess, culminating at 20:17:40 UTC on 20th July 1969 when Apollo 11 touched down on the surface of the Moon.  In the 42 years since that momentous occasion we have seen numerous robotic missions to the planets and, for the last 30 years, regular forays into near Earth orbit of the NASA Space Shuttles which have delivered and maintained the great telescopes and, for the last decade or so, have contributed to the construction of the ISS. Along the way there have been many triumphs, but we should never forget the human cost:

Apollo 1, Soyuz 1, Soyuz 11,  Challenger, Columbia – all pioneers who paid the ultimate sacrifice.

As someone who was born less than a year since Garagin took that flight, I’ve long had an interest in space – be it spaceflight or astronomy and remember the heady days of the Apollo programme and the wonder of knowing that a quarter of a million miles away (give or take) on the Moon there were humans walking about.  In those days, of course, there were far fewer satellites in orbit and you needed the finances of a small country to afford the sort of telescope that’s commonly available nowadays.  If you were lucky and happened to be looking in the right place at the right time you’d see a dot moving across the sky and maybe realise that was a satellite. That was how it was for me until one evening last summer when I happened to look up and see a swiftly moving dot followed by a much brighter object.  I was somewhat mystified at the time as I didn’t for one moment think it was what it turned out to be: a Progress supply vessel followed by the International Space Station!

Since then, I’ve tried to keep track of when the ISS is due over and have been fortunate to capture it in passing.  Sadly, as the Shuttle era draws to a close I’ve not been able to grab an image of ISS and Shuttle either docked or before/after docking.  Maybe when Atlantis takes its last flight I’ll get a chance. Why all the fuss about the ISS? Well, I think it’s to do with the fact it’s crewed and it’s easily seen. I’m not sure whether, in their time, SkyLab, Salyut or Mir were ever visible from the UK or whether anyone was able to image them, but the ISS is unmistakable and, with suitable equipment it’s possible totake a picture showing its progress across the sky.  The ultimate challenge, though, is to capture an image of the ISS not as a streak across the sky but a snapshot, so that is my next project.  Hopefully I’ll be able to post the results soon!