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Wednesday, October 14, 2015

Things that are far away

Things that appear to be close to each other in the night sky may be very far from each other.


What Distance (ly)
Vega 25
Capella 42
Dumbbell 1360
Andromeda 2500000
Triangulum 3000000

Vega. 15s shutter, ISO 8000
Capella. 25s shutter, ISO 8000

Dumbbell nebula. 30s shutter, ISO 10000
Andromeda galaxy. 30s shutter, ISO 8000
Triangulum galaxy. 30s shutter, ISO 10000


(Sometimes when I write shutter I accidentally write shitter)

Monday, November 25, 2013

Looking at the sky

Yes, that is snow on the ground.
I think I may have figured out how to use the EQ3 Synscan thingie. My telescope now finds stars for me. I no longer have to find them myself.

Wednesday, November 13, 2013

Size matters

Some calculations will seem very intimidating at first. They won't bite.

Telescope


\[\text{Diameter of mirror, }D_1 = 150 mm\] \[\text{Focal length of mirror, }f_1 = 750 mm\] \[\text{Focal length of eyepiece, }f_2 = 28 mm\] \[\text{Resulting magnification}\frac{f_1}{f_2}=\frac{750}{28}\approx{27}\] \[\text{f-number, }N = \frac{f_1}{D_1}=\frac{150}{750}=5\]

Next up is a concept I don't fully understand. Macimum theoretical resolution of a telescope. Capability to see small details. This is apparently a function of telescope diameter and light wavelength. At least in theory. Stuff like aberrations and seeing come in the way, but there is a maximum theoretical resolution. For visual light we get

\[\alpha = \frac{140}{D_1} = \frac{140}{150} \approx 0.93 \text{ arcseconds}\]

So, I won't be able to distinguish details smaller than about 1 arcsecond. For reference, the moon is about 30 arcminutes.

Camera

The telescope is interesting in itself. Let's see what happens if we attach a camera to the telescope. First we figure out the plate scale measured in arc seconds per mm.

\[\text{Width } 3888 \text{ px}; 22,2 \text{mm}\] \[\text{Heigth } 2592 \text{ px}; 14,8 \text{mm}\]

\[\text{Plate scale } = \frac{206 265}{f_1} = \frac{206 265}{750} \approx 275 \text{ arc seconds per mm}\]

Sooo... images I take with my camera will be roughly 1,7 by 1,1 arch degrees.  The moons diameter is roughly half an arch degree. This seems to be in line with my first experimental photos. Waiting for the moon to come up so veryify this. Moon, where are you?

What about resolution?

\[ 1,7 \text{ arc degree divided by } 3888 \text{ pixels gives roughly 2292 pixels per arch degree}\] \[\text{or } 0,63 \text{ pixels per arch second}\]
Seems the camera resolution is comparable to the telescopes theoretical maximum resolution. Cool.

Sunday, November 10, 2013

Sky image 4

Look at me! I have four moons. You only have one.

Jupiter, with moons Ganymede, Io, Europa and Callisto.

Finally got the motor on the polar axis running. Just a few more kgs to carry around.

ISO 100, 30s exposure.

Yes, that's right! 30s exposure with no trails!

Unfortunately we had some clouds come in over our sky just as we were getting everything set up. The halo is hopefully a cloud, not an aberration in the scope.

#astronomy #jupiter #telescope

Friday, November 8, 2013

Sky image 3

The Pleiades - gotta catch 'em all!
The Pleiades, M45. Thought to be some 400 light years away.

I do like their names. Alcyone, Celaeno, Electra, Atlas, Merope, Asterope I & II, Taygeta, Maia, and Pleione.

ISO 1600, 1/2s

Can't take longer exposures currently. Haven't hooked up my battery to the motor that rotates the telescope.

#astronomy #pleiades #canon #skywatcher #astrophotography

Tuesday, November 5, 2013

Sky Image 2

I am the Andromeda galaxy. I can see your house from here.
Andromeda galaxy, M31.
Believed to be 2.5 million light years away.

ISO 1600, 8s exposure

Can't take longer exposures currently. Haven't hooked up my battery to the motor that rotates the telescope.

#astronomy #galaxy #telescope #canon #andromeda #astrophotography #skywatcher

Sunday, November 3, 2013

Sky Image 1

I am jupiter. I bid you to sacrifice a white castrated bull in my name.
Jupiter with its moons Callisto, Europa and Ganymede.

ISO 800, 2s exposure.

Can't take longer exposures currently. Haven't hooked up my battery to the motor that rotates the telescope.

Friday, November 1, 2013

Using Canon 400D Digital Rebel XTi for astrophotography

When shopping for a telescope one of the first questions that came to my mind was how to attach the camera to the telescope. Do I duct tape the camera to the eyepiece? Turns out the answer is no and that there is a fairly accepted standard way to do this. Most telescopes seem to have a standardized eyepiece socket. All I had to do was to get something called a T2 ring compatible with my camera and hook it up. See wikipedia http://en.wikipedia.org/wiki/T-mount

Apparently this does not always work. Since the CCD is so far back in the camera it will never come into focus. I was lucky enough to buy a telescope of the Skywatcher brand. They apparently have a clever eyepiece socket that allows me to shorten the distance between the camera and the secondary mirror getting the CCD into focus.

Hello, I am a street lamp

I took a first picture of a street lamp outside my apartment on my first attempt to hook things up. I'm not sure why it's so blurred. I've got three theories:
  • There are several layers of glass windows between the telescope and the street lamp. I live in northern Sweden, remember? My windows have got three layers of glass and the shot is out through the balcony window. I have an extra layer of windows there. So four layers of glass.
  • The rig was shaking. I used my hand to press the trigger on the camera. 
  • Camera was simply not in focus. It's kind of hard to see through the small viewfinder in the camera.
I think the solution to the latter two problems is to hook my camera up to a computer and use it to take shots. More about that in a later post. I think the solution to the first problem is to go outside. More about that in later posts too.

Wednesday, October 30, 2013

New blog subject: Backyard astronomy

This blog has changed subjects a few times already and may do so again. This time it's because I've bought myself a brand new telescope and I wish to write about it. Perhaps not so much about the telescope but rather about how I learn to use it and what I can observe in it.

You put your weed in there.
What do I intend to do with it? Look at stars (white dots in the eyepiece), look at planets (large white dots in the eyepiece), look at deep sky objects (fuzzy white blobs in the eyepiece) and look at the moon (looks the same, but bigger). I also intend to take pictures of these objects. I have a normal Canon DSLR that's at least 5 years old. It's called Canon EOS 400D in most of the world but apparently Digital Rebel XTi in North America and EOS Kiss Digital X in Japan. More about Canons weird decisions in later posts. Will I buy a new camera just to take pictures of the night sky? Probably not.

Will I post all my results here? Yes. Good ones - and bad.

Sunday, January 13, 2013

Pensionspengar som beter sig som folk?


Bakgrund
Jag har nyligen hamnat i en situation där jag får sätta en del av mina pensionspengar direkt i aktier. Jag har inte till fullo begripit reglerna, men de verkar involvera: köp aktier och fonder, inga derivat eller blankning. Bara aktier i Norden, USA och Kanada är tillgängliga.
Något inspirerad av Sara Granérs teckning ovan (hmm upphovsrättsintrång) tänkte jag läsa på lite vad mina pensionspengar gör egentligen. En fond som är investerad i alla bolag på Stockholmsbörsen kommer ju att investera både etiska och oetika bolag. Min idé blev helt enkelt att dela upp alla börsnoterade bolag i tre listor beroende på vad de håller på med.

Vaddå etiskt?
Till "goda listan" söker jag bolag som jag upplever driver samhället i en positiv riktning. Gärna bolag som inte behöver en länk om "CSR" på sin framsida, för att tanken på att inte bete sig som en total psykopat är självklar inom hela bolaget.
Till "svata listan" hamnar bolag som beter sig osedvanligt grisigt åt. T.ex. SAAB som har för vana att muta fattiga länder att köpa vapen. Eller bolag i Lundin-sfären som inte drar sig för att samarbeta med grymma diktaturer för att exploatera naturresurser.
En majoritet av bolagen hamnade ändå i nån slags mellanläge. Normala företag som inte riktigt platsar in på någon av de andra två.

Gränsdragning
Man kan ägna ett liv på att inspektera vad varje bolag håller på med och ändå inte komma fram till vad som är bra och dåligt. Somliga bolag utger sig för att tillverka läkemedel som hjälper folk, men är i själva verket bara patent-troll. Och vad säger vi om investmentbolag som investerar i fattigare länder? Jobb-skapare eller nykolonialister?

Varför?
Syftet är alltså inte att maximera vinst på investerat kapital. Vill man göra det kan man köpa en kniv och råna folk vid en bankomat. Ett beteende jag anser vara i samma moraliska klass som Lundin-sfären eller SAABs. Syftet är heller inte att försöka göra världen till en bättre plats. Det är ju faktiskt inte så att det kommer att gå bättre för bolagen bara för att folk köper deras aktier. Syftet är att genom att ha en någorlunda bred aktieportfölj någorlunda kunna följa börs-index utan att behöva ha blod på händerna.

Nog skitsnack! Ge mig listorna!
Snart, snart. Bara en sak till. Några av bolagen, framförallt de mindre verkar just nu vara riktigt dåliga investeringar. Innan du springer iväg och sätter hela ditt pensionskapital i de här bolagen får du lov att ta en titt på deras fundamenta. Några av de mindre bolagen är mer eller mindre i konkurs-läge.

Goda listan
2E Group
Aerocrine B
Allenex
Arise Windpower
Artimplant B
Bore Tech
Boule Diagnostics
Cavotec SA
CellaVision
ChronTech Pharma
Coastal Contacts Inc
Elekta B
Enea
Eolus Vind B
Epicept
Episurf Medical B
Etrion
EXINI Diagnostics
Fenix Outdoor B
FinnvedenBulten
Getinge B
Hifab B
Karo Bio
Kinnevik A
Lightlab Sweden B
Meda A
Millicom International Cellular SDB
Moberg Derma
Morphic Technologies B
Opcon
Ortivus A
Pilum B
RaySearch Laboratories B
Skåne-möllan
SkiStar B
Sweco A
Swedish Orphan Biovitrum
Wallenstam B
Xvivo Perfusion

Svarta listan
A-Com
ABB
Africa Oil Corp.
Alliance Oil Company SDB
Alpcot Agro
Aqeri Holding
Arcam
Arctic Gold
Auriant Mining AB
AVTECH Sweden B
Axis
Betsson B
Betting Promotion Sweden AB
Black Earth Farming SDB
BlackPearl Resources SDB
Bringwell
Cision
Cloetta
Concordia Maritime B
Confidence International AB
CybAero
Dedicare
Diadrom Holding
EnQuest PLC
EOS Russia
eWork Scandinavia
Generic Sweden
Global Health Partner
Holmen A
Intellecta B
Investor B
Invisio Communications
JLT Mobile Computers
Kopy Goldfields
Lucara Diamond Corp
Lundin Mining Corporation SDB
Lundin Petroleum
Mackmyra Svensk Whisky
Mediaprovider
Micro Systemation B
Midsona B
Misen Energy AB
MTG B
multiQ International
Net Entertainment B
New Nordic Healthbrands
Nordic Leisure AB
Nordic Service Partners Holding B
Nordkom AB
Opus Group AB
Pallas Group
Partnertech
PetroGrand
Poolia B
Proffice B
Ruric B
RusForest
SAAB B
Securitas B
Selena Oil & Gas Holding
Semafo Inc.
ShaMaran Petroleum Corp
Shelton Petroleum AB B
Swedish Match
Tethys Oil
Trigon Agri
Trygga Hem Skandinavien
Uniflex B
Victoria Park
Vostok Nafta Investment SDB
Wise Group
ZetaDisplay

Nu då?
Jag har bara snabbt tittat igenom bolagen på Stockholm large, mid, small cap och First North. Kvar är Aktietorget, samt alla bolag i Norge, Danmark, Finland, USA och Kanada. Det blir ett par arbetstimmar. Bolagen har även den otrevliga vanan att hoppa mellan listor så jag måste hålla ögonen på den typen av förflyttningar med.

Frågor? Feedback? Jag håller koll på kommentarsfältet.