Re: Tonight's APOD photo

trucker743 · Post by **trucker743** » Tue Oct 16, 2007 4:18 am

Can anyone explain to me why stars A, B and C - and the bright object near the supernova look much brighter in the left, or before, photo? I would have thought they'd need to be exposed at the same level to get a true comparison.

A Totally Uneducated Observer Who Still Gets Curious

rollovermikey · Post by **rollovermikey** » Tue Oct 16, 2007 4:42 am

Could anyone enlighten me as to exactly where this supernova emmanated from? You know, like in or near what constellation?

bluegreenheart · Post by **bluegreenheart** » Tue Oct 16, 2007 5:34 am

In the "before" image, a little past half way toward the bright star to the left of the letter A, you see a blotch of light that is not present in the "after" image. Instead, there appears to be a streak, perhaps a tail, going directly toward the supernova. I wonder if SM2005ap is in fact visible in both images. It would be interesting to see images taken prior to the "before" and following the "after" images.

Case · Post by **Case** » Tue Oct 16, 2007 5:39 am

In Coma Berenices, according to the press release.
R.A. = 13h01m14.84s, Dec. = +27°43'31.4" (or R.A. = 195.31183°, Dec. = 27.72539°)
to be precise...

SDSS color image ("before") with noise reduction.

Case · Post by **Case** » Tue Oct 16, 2007 5:47 am

trucker743 wrote:why [do they] look much brighter in the left photo?

The photo on the left is from the Sloan Digital Sky Survey, based in New Mexico, the one on the right is from the Hobby-Eberly Telescope, based in Texas. Different telescopes, different locations, different weather - no wonder there are slight differences in the photos.

TimeTravel123456789 · Post by **TimeTravel123456789** » Tue Oct 16, 2007 2:42 pm

I am not sure this is not a novae rather than Supernovae.

Look at C and D dimming with A brightening. Why Supernovae versus novae.

Has this been seen by many observatories?

SN 1987 A certainly was, but has this been observed multiple times.

I learned this summer how our constitution is about the right of judges to threaten jail when you express concern with rights. I did not know that. They helped me understand the American Legal System.

geckzilla · Post by **geckzilla** » Tue Oct 16, 2007 2:53 pm

The other stars are not necessarily dimming... rather, the levels in the photograph were shifted by the brightening of the supernova which only makes them seem dimmer. Also, A is not the supernova. The supernova appears above and to the right of A.

ta152h0 · Post by **ta152h0** » Tue Oct 16, 2007 3:04 pm

Is it a matter of luck there is a " before " image at the exact spot this thing blew up ? Were there hints there was going gto be an event ?

Chris Peterson · Post by **Chris Peterson** » Tue Oct 16, 2007 4:06 pm

ta152h0 wrote:Is it a matter of luck there is a " before " image at the exact spot this thing blew up ? Were there hints there was going gto be an event ?

There have been many photographic all sky surveys. For the most part, there are images of the entire sky available, so there are "before" images whenever a supernova happens.

Where luck comes in is the rare case where a supernova area gets imaged just before the event is detected, such that the early stages are caught. That's not the case here.

trucker743 · Post by **trucker743** » Tue Oct 16, 2007 7:14 pm

Makes perfect sense! Thanks - Hope I wasn't a bother!

Totally Uneducated

iamlucky13 · Post by **iamlucky13** » Tue Oct 16, 2007 11:48 pm

The blotch is there, but dimmer, apparently another star. If you compare all the stars in the before and after, you will notice the after image is dimmer. I don't know what the perceived tail is, but my best guess is a compression artifact or random noise. I'm not sure whether that background fuzz is noise or fainter stars.

The star that caused SN2005ap would not have been visible before the supernova. Assuming the red-shift distance method is correct, it's 5 billion light years away. Individual stars become impossible to distinguish with our best telescopes at distances even a small fraction of that (some where on the order of 100,000 LY, I think). Even a long Hubble exposure would have only faintly showed the galaxy the source star resides in. In fact, it seems this single star briefly outshone its entire parent galaxy.

TimeTravel123456789 · Post by **TimeTravel123456789** » Thu Oct 18, 2007 12:56 pm

Several of us have observed differences between Hobbel Ebberly and SDSS besides the alleged Supernovae.

It might be good if the Michigan Technical University or other NASA staff involved in Astronomy picutre of the day posted a before and after image from

SDSS

Before and After or now

Hobbell Eberly

Before and After Now

Just to study consistency in photos and differences between telescopes and observations. This is helpful conversation for me. All I meant is I learned about governments violating rights more; I was not as aware in a personal way of that even though I should have understood that better.

James T. Struck

Case · Post by **Case** » Thu Oct 18, 2007 1:23 pm

TimeTravel123456789 wrote:It might be good if they posted a before and after image from the same telescope

The problem is that supernovas fade pretty quickly; fading from view over several weeks or months. A SN from 2005 at 4.7 billion light-years would now be as invisible as before discovery. Archive photos are all we have.
I doubt your comparison-curiosity will be enough for precious telescope time, at a piece of the sky where there is nothing to see.

Starship Asterisk*