Astrophotography on the (relative) cheap

Having a rare clear night helps when in the Netherlands. Doubly so if circumstances are such that one can have in one’s sight a couple of “standard” astro-photo targets such as M31, our nearest (proper) galactic neighbor, and a really good open star cluster, in this case the Double-Double cluster.

I use a Meade ETX-80 scope, paired with a Canon 1100-D DSLR. With such a setup, long exposures are a no-no, and the results of my run will serve to demonstrate this fact.

Take a look at the final image of M31; it is an equivalent of a 2 minute guided exposure, obtained by stacking a number of individual 2 second exposures. This is the limit of the tracking accuracy of my mount, which makes it almost redundant.

M31 - 2 min. stack

M31 – 2 min. stack

I have imaged using the raw (CR2) format, readout noise subtraction done in camera. Stacking was done using the free Deep Sky stacker (dark and bias frames applied, no flats). The CR2 images were first converted to the DNG format (the DNG converter tool – standard feature of the Astro Distro Linux did that). The stack was saved as a FITS file (a cube actually, one plane per color) and then re-composited into a color image using DS9 (log scaling with an exponent of 3000). The color scaling was done by eye, I don’t claim that I have achieved the correct color multipliers. Finally, the end result was exported as a JPG file, scaled and saved as a PNG for publishing.

Pushing the setup to the limit of the noise has its consequences, as is plainly visible. Visible are also the remaining hot pixels which were formed into snakelike artifacts by the stacking. The two satellites of M31 are also apparent, as is a hint of the disk and some of the dust in it. M31 has a very bright bulge, and we almost always see that (with amateur scopes anyway) thinking that it is the whole thing. It is not.

Now, here is what I got with in-perfect tracking, exposing for 2 minutes, no stacking, same setup. The image was converted from CR2 to DNG format and processed in the Gimp (its DNG plugin does wonders by the way):

M31 trails

M31 trails

This was much more straight forward. Reason? The signal to noise was much better (understandably). So, stacking can only do so much. Especially for faint targets. In this case, I bet that a stack of say 20 2 minute exposures even with trailing stars would  benefit the Andromeda galaxy. It is already a blur, so who cares, right? 😉 I might do such a project…

Same, but for the Double-Double cluster in Perseus:

Double Cluster

Double Cluster

 

Double Cluster trails

Double Cluster trails

CLOSING TIME

Ah we’re drinking and we’re dancing
and the band is really happening
and the Johnny Walker wisdom running high
And my very sweet companion
she’s the Angel of Compassion
she’s rubbing half the world against her thigh
And every drinker every dancer
lifts a happy face to thank her
the fiddler fiddles something so sublime
all the women tear their blouses off
and the men they dance on the polka-dots
and it’s partner found, it’s partner lost
and it’s hell to pay when the fiddler stops:
it’s CLOSING TIME
Yeah the women tear their blouses off
and the men they dance on the polka-dots
and it’s partner found, it’s partner lost
and it’s hell to pay when the fiddler stops:
it’s CLOSING TIME

Ah we’re lonely, we’re romantic
and the cider’s laced with acid
and the Holy Spirit’s crying, “Where’s the beef?”
And the moon is swimming naked
and the summer night is fragrant
with a mighty expectation of relief
So we struggle and we stagger
down the snakes and up the ladder
to the tower where the blessed hours chime
and I swear it happened just like this:
a sigh, a cry, a hungry kiss
the Gates of Love they budged an inch
I can’t say much has happened since
but CLOSING TIME

I swear it happened just like this:
a sigh, a cry, a hungry kiss
the Gates of Love they budged an inch
I can’t say much has happened since
CLOSING TIME

I loved you for your beauty
but that doesn’t make a fool of me:
you were in it for your beauty too
and I loved you for your body
there’s a voice that sounds like God to me
declaring, declaring, declaring that your body’s really you
And I loved you when our love was blessed
and I love you now there’s nothing left
but sorrow and a sense of overtime
and I missed you since the place got wrecked
And I just don’t care what happens next
looks like freedom but it feels like death
it’s something in between, I guess
it’s CLOSING TIME

Yeah I missed you since the place got wrecked
By the winds of change and the weeds of sex
looks like freedom but it feels like death
it’s something in between, I guess
it’s CLOSING TIME

Yeah we’re drinking and we’re dancing
but there’s nothing really happening
and the place is dead as Heaven on a Saturday night
And my very close companion
gets me fumbling gets me laughing
she’s a hundred but she’s wearing
something tight
and I lift my glass to the Awful Truth
which you can’t reveal to the Ears of Youth
except to say it isn’t worth a dime
And the whole damn place goes crazy twice
and it’s once for the devil and once for Christ
but the Boss don’t like these dizzy heights
we’re busted in the blinding lights,
busted in the blinding lights
of CLOSING TIME

The whole damn place goes crazy twice
and it’s once for the devil and once for Christ
but the Boss don’t like these dizzy heights
we’re busted in the blinding lights,
busted in the blinding lights
of CLOSING TIME

Oh the women tear their blouses off
and the men they dance on the polka-dots
It’s CLOSING TIME
And it’s partner found, it’s partner lost
and it’s hell to pay when the fiddler stops
It’s CLOSING TIME
I swear it happened just like this:
a sigh, a cry, a hungry kiss
It’s CLOSING TIME
The Gates of Love they budged an inch
I can’t say much has happened since
But CLOSING TIME
I loved you when our love was blessed
I love you now there’s nothing left
But CLOSING TIME
I miss you since the place got wrecked
By the winds of change and the weeds of sex…