Recent content by Andy Resnick

Crescent moon this evening @ 800mm (cropped): Deets: nikon D810 + nikkor 800/8, 1/5s, ISO 1250, straight to jpg. Maybe you prefer the 1:1 crop: (1/200s, ISO 250)

Skarnoid, Fen Complex. Partially trachytic K-feldspar in groundmass, evidence of metasomatism. Alteration of the groundmass is correlated with both a decrease in both interstitial pyroxene aggregates (possibly degraded aegirine) and loss of trachytic K-feldspar texture. Image pair: left...

I know! It's sobering to contemplate the vastness and our insignificant place in it. I typically run the image through Astrometry.net to identify Messier/NGC/IC objects, but it doesn't get all of them (for example, UGC and PGC catalogs are not included); often distant galaxies can be...

Skarnoid (altered rhomb porphyry; foid-bearing trachyandesite QAPF zone 8b), Fen complex. While the rock may appear to be igneous (the groundmass consists of trachytic laths of feldspar and blocky phenocrysts), garnet (var. andrasite) is present so this is a metamorphic/metasomatic rock. Taken...

Final image, ready for printing, of the Virgo Cluster. The image area is approximately 14 degrees on a side: At 1:1, it looks like this- The image, if square format, is 16,900 pixels on a side. Assuming your display is about 300 pixels per inch, the full image at this display format...

No sooner did I share the Virgo panorama than we just had 10 consecutive nights of clear skies. I used most of those to complete the panorama (post-processing is ongoing). I had 2 days to spare, which I used to try imaging NGC 4565- this is a 1:1 crop at 800mm focal length: (Nikkon D810 +...

Thanks! The only equipment switch is the lens (large telephoto to small macro), most of the changes are in-camera (ISO, shutter speed, EV, mirror-up shutter delay, etc. etc.). It's (unfortunately) a lot of different settings.

The next half-dozen or so samples are just beyond my ability to identify, so I have to resort to simple descriptions: Metasomatosed Rhomb porphyry (?), Fen Complex. Abundance of calcite (less than 5%) suggests this is a calc-silicate rock, and because it is fine-grained and retains the...

Rolling out of bed this morning, bleary-eyed b/c I was up way to late doing astrophotography, and I see sunlit morning dew. I have to photograph it, but I had to re-set all the camera settings while mostly asleep, so I had to 'fix in post', as they say....

Well.... I'm definitely not going to intentionally contaminate a solution (positive control).

OMG thank you! This is EXACTLY the kind of answer I was hoping for. I'm saving and printing it out for permanent reference. The exact scenario is simply "training students to work in an aseptic environment". Most of the 'stock solutions' are commercially obtained and are contamination-free...

I don't want to wander too far off topic here- I'll simply note that the protocol references "An appropriate volume of a [water] sample", and my question is specifically targeting the word "appropriate". How is that volume determined? Was it simply a guess that has been converted into accepted...

I made up 0.1 nanomolar, the reality is that even a single bacterium (or mold spore, or yeast cell, or...) is too many. I should have phrased my original question like this: "A volume of media may have a single bacterium present. How much of the volume do you need to sample to be 99%...

Skarnoid or Foid-bearing Alkali-feldspar Trachyte (?), Fen Complex. Honestly, I am not sure if this is an igneous or metasomatic rock (also, I am reconsidering Fen 267). If igneous, it is fine-grained and thus volcanic and a trachyte. If metasomatic, the texture is unclear- not quite hornfels...

Thanks to everyone for the replies, let me address them: Apparently, I grossly overstated the (maximum) contamination level- obviously, as the number of contaminants decrease, I need to sample larger and larger volumes, but that would seem to quickly approach a limit when I need to sample the...