The Solar System at large
The Sun and Moon are the two objects in our Solar System that most people will be familiar with. Of course, through the efforts of NASA with its many unmanned probes since the 1970s, we have become used to seeing images of other members of the Sun's family, particularly Jupiter and Saturn. Still, there is room for amateur observation of the planets, and modern equipment & software make it possible to capture not only incredible detail on bodies around a billion kilometres away from us, but real-time video of events such as asteroids crashing into the gas giants.
A Christmas comet - C/2011 W3 Lovejoy
Discovered on the 2nd of December by Australian amateur astronomer Terry Lovejoy, this turned out to be one of the big surprises of 2011. A member of the Kreutz family of sungrazing comets, it was expected to be destroyed by its close passage by the Sun on the 15th. However, despite its approach to within 140,000 km of the Sun's surface, it lived to tell the tale, and those in the southern hemisphere with clear skies were treated to a view of the finest comet since 2007's comet McNaught. Unfortunately, much of eastern Queensland was under cloud in the lead up to Christmas, so we missed some of the best views. Still, the clouds cleared for a few days after Christmas and all was not lost; by this time though, the comet was fading and the tail had become quite diffuse compared with its appearance just a few days earlier. The image above was taken of the morning of the 26th, around 3:40 am - about one and a quarter hours before sunrise, so twilight is brightening the horizon. The orange glow at lower right is urban lighting. Mercury is visible very close to the horizon just left of centre, with Antares to its upper right. |
This image has normal processing, and shows the X-37B experimental mini-shuttle trailed during the 10-second exposure.
There was no bright or condensed nucleus visible at the head of the comet, and 2 days later the comet had faded considerably - probably fatally injured by its close perihelion passage, around 10% of the Sun's diameter above its surface. All photographs taken at Wellington Point, Queensland. |
NASA Mars Science Laboratory & Curiosity rover launched & leaving Earth orbit
This video is a timelapse sequence covering 25 minutes, and shows an exhaust plume vented by the upper-stage Centaur booster used to cast the 1-ton spacecraft towards its destination. The Centaur appears to be right at the apex of the plume, while MSL can be seen as a separate small trail to the left of, and slightly above, the plume [although there is now some doubt about this - it might be the other way around; waiting for an answer from NASA]. The stars are drifting west while MSL heads northeast. This is similar to the first 2 videos produced (below), but with better cropping and processing.
On the way to the Red Planet
2011 November 27th Early this morning (Brisbane time), NASA launched its Mars Science Laboratory (MSL), carrying the Curiosity rover vehicle. As it circled the Earth on its way to Mars, the spacecraft was eventually visible above Australia in the skies of Brisbane, accompanied by a plume of vapour vented from the Centaur upper stage of the launch vehicle.
This image - a 10-second exposure - shows the plume and, circled, the main MSL craft [but, as mentioned above, there is now some doubt about this]. During the exposure the stars have trailed westwards while MSL has trailed to the northeast. The plume is about 0.9 degree long - about twice the apparent width of the Moon.
I watched the launch live, but didn't expect to see anything of MSL as it passed over Australia. As it happened, I was testing a lens acquired today, to see how it performed for night sky shots, and had just shot a few frames when I looked behind me and saw a large fuzzy object. My first thought was "it's a comet", but then I realised that this could be MSL, and the rapid movement virtually confirmed it.
This image - a 10-second exposure - shows the plume and, circled, the main MSL craft [but, as mentioned above, there is now some doubt about this]. During the exposure the stars have trailed westwards while MSL has trailed to the northeast. The plume is about 0.9 degree long - about twice the apparent width of the Moon.
I watched the launch live, but didn't expect to see anything of MSL as it passed over Australia. As it happened, I was testing a lens acquired today, to see how it performed for night sky shots, and had just shot a few frames when I looked behind me and saw a large fuzzy object. My first thought was "it's a comet", but then I realised that this could be MSL, and the rapid movement virtually confirmed it.
This is the 4th frame in the timelapse sequence, taken at 16:39 UT. The plume was still an easy naked-eye object at this point, although fading steadily. With sunrise just over 2 hours away, satellites in Earth orbit are becoming visible, and three can be seen in this single image. Also visible are the bright star Sirius and the open star cluster Messier 41 near the top edge, above Sirius.
My Colleague Mark Rigby writes: "The brightest satellite trail seen in the image is the SEDSat Delta rocket stage in a 535 x 1,022-km high orbit inclined at 31.4 degrees to the equator. It was used for the launch of NASA's DS-1 spacecraft and SEDSat-1 (Students for the Exploration and Development of Space, Satellite 1) from Cape Canaveral on 24 October 1998. DS1 flew past asteroid (9969) Braille on 28 July 1999 and Comet Borrelly on 22 September 2001."
So, we have a photograph of a deep-space probe heading away from Earth, with the rocket booster from another deep-space probe apparently passing by at the same time. What are the chances of that happening?
We have consulted NASA about the speed, distance, etc of the Mars craft at the time these images were taken. Mark Rigby writes again: "Thanks to NASA's Jet Propulsion Laboratory in Pasadena, California, we have some data on our sightings/images of the Mars Science Laboratory spacecraft, Centaur rocket stage and plume. The data is based on the spacecraft itself. Approximate distance and velocity relative to Brisbane when I sighted it at 2:15am Sunday, 27 November (1615 UT, 26th) - 12,000 km and 20,769 km/h, respectively [this was 15 minutes before my first sighting, and 24 minutes before I was able to start the proper timelapse sequence - DW]. For the timelapse shot by Duncan Waldron - at the beginning of the sequence (2:39am) MSL was about 20,400 km from Brisbane and moving away at 20,680 km/h. At the end of the sequence (3:05am) it was 29,100 km distant and had slowed to 19,580 km/h."
My Colleague Mark Rigby writes: "The brightest satellite trail seen in the image is the SEDSat Delta rocket stage in a 535 x 1,022-km high orbit inclined at 31.4 degrees to the equator. It was used for the launch of NASA's DS-1 spacecraft and SEDSat-1 (Students for the Exploration and Development of Space, Satellite 1) from Cape Canaveral on 24 October 1998. DS1 flew past asteroid (9969) Braille on 28 July 1999 and Comet Borrelly on 22 September 2001."
So, we have a photograph of a deep-space probe heading away from Earth, with the rocket booster from another deep-space probe apparently passing by at the same time. What are the chances of that happening?
We have consulted NASA about the speed, distance, etc of the Mars craft at the time these images were taken. Mark Rigby writes again: "Thanks to NASA's Jet Propulsion Laboratory in Pasadena, California, we have some data on our sightings/images of the Mars Science Laboratory spacecraft, Centaur rocket stage and plume. The data is based on the spacecraft itself. Approximate distance and velocity relative to Brisbane when I sighted it at 2:15am Sunday, 27 November (1615 UT, 26th) - 12,000 km and 20,769 km/h, respectively [this was 15 minutes before my first sighting, and 24 minutes before I was able to start the proper timelapse sequence - DW]. For the timelapse shot by Duncan Waldron - at the beginning of the sequence (2:39am) MSL was about 20,400 km from Brisbane and moving away at 20,680 km/h. At the end of the sequence (3:05am) it was 29,100 km distant and had slowed to 19,580 km/h."
This image is a composite of 11 separate exposures, showing the movement of MSL against the movement of the stars. 10-second exposures with 2 seconds gap between successive exposures. 2 satellite trails are visible below and to the right of the plume.
Below are 2 video clips showing the plume drifting across the sky. When I first saw it, around 02:30 AEST (16:30 UT, 26/11), it was easily visible to the unaided eye, even in a light polluted sky. By 03:00 it was barely visible in 9x63 binoculars, although it was still visible in photographs taken up to 03:05. The second clip is just a detailed section of the main one (and slightly shorter); in it can be seen a number of satellites flashing through the field of view.
The first clip is composed of the original images, without any cropping or processing. The second clip uses images that have been cropped and slightly enhanced; it also covers a shorter period of time.
Below are 2 video clips showing the plume drifting across the sky. When I first saw it, around 02:30 AEST (16:30 UT, 26/11), it was easily visible to the unaided eye, even in a light polluted sky. By 03:00 it was barely visible in 9x63 binoculars, although it was still visible in photographs taken up to 03:05. The second clip is just a detailed section of the main one (and slightly shorter); in it can be seen a number of satellites flashing through the field of view.
The first clip is composed of the original images, without any cropping or processing. The second clip uses images that have been cropped and slightly enhanced; it also covers a shorter period of time.
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Curiosity and the Mars Science Lab gliding through the stars of Lepus the hare. The upper half of the image contains the lower half of Orion; the Orion Nebula is visible, in the Sword, and two of the Belt stars are seen right at the top. The bright supergiant star Rigel is at upper right, close to the edge. This is the 'correct' northern hemisphere view, where Orion's sword actually hangs downwards, assisted by gravity, in the time-honoured fashion.
Visiting distant family
2011 November 12th, 22:19-24 AEST. Jupiter is just past opposition, so is currently visible throughout the night. It has largely recovered from the disappearance of its south equatorial belt last year, although that now appears rather broad and diffuse compared with its northern neighbour. A blend of 7 images, the shooting details are similar to the image below.
Having dealt with Jupiter, I turned my attention briefly to Uranus. The first planet to be discovered in recorded history, Uranus is certainly not an obvious object. Normally hovering around the limit of naked-eye visibility, it will go unnoticed unless you go looking for it, and even then, it will be a minuscule and unassuming object. With good seeing and a good telescope, it will be clear that is not a star, but you won't be able to tell much more about it - like, it has several moons. "Will I be able to photograph any of them?" I wondered, and there was only one way to find out. A range of exposures up to 30 sec. at ISO 400 showed a bright planetary image, but I couldn't tell any more until I opened the image in the PC.
The image below shows an enhanced image from the longest exposure, plus a comparison image from Stellarium. I'm pretty confident that I've recorded two of the moons, while the third speck to the right of the overexposed Uranus could be image noise, but I reckon it is the faint trace of Umbriel. Later this month I'll try a few more exposures on different nights, with better placing of the brightest moons, so that should confirm my success. Or not.
Having dealt with Jupiter, I turned my attention briefly to Uranus. The first planet to be discovered in recorded history, Uranus is certainly not an obvious object. Normally hovering around the limit of naked-eye visibility, it will go unnoticed unless you go looking for it, and even then, it will be a minuscule and unassuming object. With good seeing and a good telescope, it will be clear that is not a star, but you won't be able to tell much more about it - like, it has several moons. "Will I be able to photograph any of them?" I wondered, and there was only one way to find out. A range of exposures up to 30 sec. at ISO 400 showed a bright planetary image, but I couldn't tell any more until I opened the image in the PC.
The image below shows an enhanced image from the longest exposure, plus a comparison image from Stellarium. I'm pretty confident that I've recorded two of the moons, while the third speck to the right of the overexposed Uranus could be image noise, but I reckon it is the faint trace of Umbriel. Later this month I'll try a few more exposures on different nights, with better placing of the brightest moons, so that should confirm my success. Or not.
Uranus is the brightest object, and is shown with an enlarged detail inset. Likely images of 3 moons are indicated, compared with their positions as given by Stellarium. Titania is not shown - it would have been within the overexposed disk of Uranus; there is however a drive error artifact, that happens to be roughly where Titania should be.
Four big moons, by Jove
2011 November 3rd, 20:28 AEST. Another full family portrait taken this time with the Zeiss 150 mm. Instead of prime focus, I used a 2x teleconverter to extend the focal length to 4500 mm, and the focal ratio to f/30. This gave a usably large image - around 1.1mm, or 175 pixels. It left a lot of empty space on the APS-C sensor, but the image scale was perfect for the distance between Ganymede and Callisto. From left, the moons are: Ganymede, Io, Europa & Callisto.
This is effectively a single image of the disk, but I have actually used two images: one exposed for the planet (1/10 sec.), the other for the four moons (1/3 sec.); ISO800. Unsharp masking was used to improve the image quality (the original had no sharpening in camera), but nothing else has been done.
The difference in quality between this image and the one below is quite apparent. That is due in part to the smaller image scale in the earlier one (1200 mm instead of 4500), but there is also a general lack of sharpness in that image. It was also taken with Jupiter at lower altitude, so atmospheric effects would have been greater too.
This is effectively a single image of the disk, but I have actually used two images: one exposed for the planet (1/10 sec.), the other for the four moons (1/3 sec.); ISO800. Unsharp masking was used to improve the image quality (the original had no sharpening in camera), but nothing else has been done.
The difference in quality between this image and the one below is quite apparent. That is due in part to the smaller image scale in the earlier one (1200 mm instead of 4500), but there is also a general lack of sharpness in that image. It was also taken with Jupiter at lower altitude, so atmospheric effects would have been greater too.
Eppur si muove*
2011 October 12th, 20:53-21:01 AEST. Jupiter, caught with the 4 moons that got Galileo into so much hot water. When he observed the planet in 1610, it became apparent to him that Jupiter was accompanied by 4 smaller bodies, orbiting the planet itself. This was a historic discovery, as it was confirmation of the validity of the Copernican system, which postulated that the Earth was not at the centre of everything, merely one of the planets orbiting the Sun. Of course, this didn't go down well with the Church, and it wasn't until 1992 that a papal apology for his treatment was issued.
This is a combination of several prime focus images, 4 of 1/180 second to record the planet detail, and 2 of 1/8 and 1/15 second, to record the 4 moons. Prime focus imaging of the planets is not ideal, because of the small image scale, but eyepiece projection to give a larger image wasn't an option at this time. In increasing distance from the planet are: Io, Europa, Ganymede and Callisto.
Taken with a 150 mm reflector, 1200 mm focal length.
(* A legend exists that at his trial, Galileo muttered "And yet it does move" - a reference to his belief that the Earth was not static; sadly, the legend is likely false.)
This is a combination of several prime focus images, 4 of 1/180 second to record the planet detail, and 2 of 1/8 and 1/15 second, to record the 4 moons. Prime focus imaging of the planets is not ideal, because of the small image scale, but eyepiece projection to give a larger image wasn't an option at this time. In increasing distance from the planet are: Io, Europa, Ganymede and Callisto.
Taken with a 150 mm reflector, 1200 mm focal length.
(* A legend exists that at his trial, Galileo muttered "And yet it does move" - a reference to his belief that the Earth was not static; sadly, the legend is likely false.)
Catching dim light from afar
I was finally able to have a couple of attempts at photographing Pluto. I wasn't sure how well I'd be able to locate the area for photography, let alone record the mag. 14 object. The night sky from the Brisbane Planetarium is a bit on the bright side, to say the least, and it can be a challenge to locate all but the brighter stars and nebulae with the 10x40 finder; M8 can just be seen, M7 is difficult, and M20 impossible. Fortunately, with a finder chart printed from a Stellarium screenshot, I was able to locate the right area very easily; Pluto being close to a distinctive group of stars helped as well.
The first attempt was on Sept 30th; five 1-minute exposures show Pluto very clearly. Following up with another three exposures on Oct 1st, the seeing seems to have been rather better, giving smaller star images; the movement of Pluto over 24 hours can be seen. It hasn't gone far - about half a minute of arc, equal to one-sixtieth of the Moon's apparent diameter. The image shows exposures from each night, compared with a Stellarium screenshot for Oct 1.
The first attempt was on Sept 30th; five 1-minute exposures show Pluto very clearly. Following up with another three exposures on Oct 1st, the seeing seems to have been rather better, giving smaller star images; the movement of Pluto over 24 hours can be seen. It hasn't gone far - about half a minute of arc, equal to one-sixtieth of the Moon's apparent diameter. The image shows exposures from each night, compared with a Stellarium screenshot for Oct 1.
Here's an animation of the 2 sets of images, showing the motion.
I used DeepSkyStacker to combine the sets of images, with dark, flat and bias frames for each. The Zeiss tracking seems to be spot-on, at least for these exposures, although my first impression earlier this year was that there was significant drift in a matter of minutes; there seems to be provision for adjusting the RA drive rate, but it doesn't seem to be working. Further tests with longer exposures may tell me the truth. Of course, a proper CCD camera with autoguider capability would be ideal, but there's no budget for that just now.
If I can manage 5-minute exposures, then I might be able to reach my own 2 asteroids, (3753) Cruithne and (5577) Priestley, plus asteroid (5277) Brisbane, which are around mag. 17, 16.5 and 17.5 respectively, at the moment. They will be visually unexciting, but it will be satisfying to be able to capture objects that have a personal connection. I reckon I'm reaching around 15.5 with 1-minute exposures, so 17 should be within reach, if the drive is up to it.
I used DeepSkyStacker to combine the sets of images, with dark, flat and bias frames for each. The Zeiss tracking seems to be spot-on, at least for these exposures, although my first impression earlier this year was that there was significant drift in a matter of minutes; there seems to be provision for adjusting the RA drive rate, but it doesn't seem to be working. Further tests with longer exposures may tell me the truth. Of course, a proper CCD camera with autoguider capability would be ideal, but there's no budget for that just now.
If I can manage 5-minute exposures, then I might be able to reach my own 2 asteroids, (3753) Cruithne and (5577) Priestley, plus asteroid (5277) Brisbane, which are around mag. 17, 16.5 and 17.5 respectively, at the moment. They will be visually unexciting, but it will be satisfying to be able to capture objects that have a personal connection. I reckon I'm reaching around 15.5 with 1-minute exposures, so 17 should be within reach, if the drive is up to it.
Variable stars?
Looking at the Pluto images, there is a couple of stars that seem to be brighter than given by Stellarium; are they variables? There is no noticeable difference in brightness between the 30 Sept and 1 Oct exposures above, so the recorded appearance is genuine. The two suspect stars are marked with horizontal bars, and comparison stars marked with vertical bars. See the Stellarium screenshots below, for nominal magnitude values; each of the suspects is around 1.8 mag. brighter than stated by Stellarium.
Stellarium screenshots
