Nova 2005 Sgr #2 - obs rep & charts

Object: AAVSO1811-30N Sgr 05 #2
Date: 2005.07 6:58 UTC JD 2453563.7903
Az-Alt: Meridian approx. 18=B0
Position: J181750.77-302631.2 w/i 1.5=B0 southwest of del Sgr

Magnitude measured: 9.9 true mag.(extinct. adj. mag); apparent 10.4
AAVSO reported ranges for JD 2453562-63 a 9.1-9.5
See
http://www.aavso.org/cgi-bin/searchc...20sgr%2005%232
(Difference attributed to light pollution at observing site)

Magnitude trend: Nova continues to dim from v8.0 on JD2453559 (approx.
4 days), but is easily visible with small aperatures (70mm) in low
light polluted skies. Based on the AAVSO light curve trend, that is a
linear rate of roughly 0.3 mags per day ( (9.5-8.0)/5) ). The later
setting moon will make observations increasingly more difficult until
the sky is washed-out around July 15.

Observing point: Little Mountain Pass, 10 miles east of Salt Lake City,
Utah, Latitude N 40.8, Longitude W 111.9, Altitude approx. 7700 ft.
(2347 meters)

Scope: 20x70 binoculars, parallelogram mount, 1.5=B0 x 1=B0 TFOV.

Charts: Tirion Cambridge Atlas #18; Sky Atlas 2000 #22; AAVSO Variable
Star Atlas (2nd 1990) #144. The Cartes de Ciel data listing provided
visual magnitudes. For most Tycho stars, Cartes du Ciel reports
magnitudes converted from the Tycho system to visual system.

Supplemental finding charts - notes:

- Area orienting 4 deg area finder
http://members.csolutions.net/fisher...05_2/NSgr05_2=
_4d.gif

From del Sgr, first establish the asterism triangle between del Sgr,
HD169586 and 18 Sgr. The del Sgr to HD169586 line is broken by optical
doubles HD169377 and HD169337. The del Sgr to 18 Sgr line is broken by
globular NGC 6624 (v8.3, dia. 6').
http://members.csolutions.net/fisher...05_2/NSgr05_2=
_4dB.gif


This first asterism triangle distinguishes 18 Sgr from nearby HD168493
(7.0).

Establish a second asterism triangle between del Sgr, 18 del and
HD168493 (7.0). The asterism line bewteen del Sgr and HD168493 is
broken by a small arc asterism including HD319330 (9.6). This second
asterism line is used to distinguish between two stars 1/4=B0 south of
del Sgr: HD168576 (8.2) and HD168399 (8.9).

Other large and useful asterisms within 2.5=B0 of del Sgr a
1) a triangle including HD167382 (7.3), and,
2) a 1/2=B0 arc including HD166470 (7.7).

- 2 deg area finder
http://members.csolutions.net/fisher...05_2/NSgr05_2=
_2d.gif

First, establish the small 1/4=B0 triangle asterism defined by del Sgr,
HD168576 (8.2) and HD168399 (8.9).
http://members.csolutions.net/fisher...05_2/NSgr05_2=
_2dB.gif

Second, along the asterism line between HD168493 (7.0) to HD167441
(7.8), find the two sets of optical doubles. The first is defined by
HD319238 and HD167845; the second by HD167706 and TYC7392-01064-1.
This second set of optical doubles is within a 1/4=B0 of AAVSO1811-30N
Sgr 05 #2.

The nova will appear to be at or next to the position of
TYC7392-00980-1 (10.95), but is clearly much brighter than magnitude
10.9.

Estimating magnitudes using detail charts:

- AAVSO detail chart -
http://www.aavso.org/cgi-bin/shrinkw...NSGR05_2/NSGR=
05_2-D.PNG

- Supplemental chart provided here -
http://members.csolutions.net/fisher...05_2/NSgr05_2=
_2dC.gif

Using the supplemental chart, establish the "outer" arc asterism
defined by TCY392-00404-1 (10.17), GSC7392.722, and TYC39300384-1
(10.2).

Then establish the "inner" arc asterism defined by TCY392-00404-1
(10.17), star labelled at magnitude 101 in the AAVSO detail chart, and
TYC39300831-1 (10.53).

The corresponding stars of the "inner" arc are labelled on the AAVSO
detail chart with magnitudes 78, 101 and 103.

Magnitude 10.9 star TYC392-00980-1 plots about 6 arcminutes below the
nova. Currently (7/12), the nova is distinctly brighter and easily
distinguished from the TYC392-00980-1.

Magnitude estimation notes:

v10.95 TYC7392-00980-1 was not visible in the FOV.

Nova 1811-30 Sgr 05 #2 was brighter than "inner arc" stars
TYC7392-00404-1 (10.17), TYC7393-00831-1 (10.53) but dimmer than
HD167524 (9.39), HD319238 (9.64), HD167616 (9.6), and TYC7392-01964-1
(9.87).

Extrafocal extinction was used on the immediate TFOV to locate the best
match. Star HD167753 (9.9) appeared to be the closest matching star.
See -
http://members.csolutions.net/fisher...05_2/NSgr05_2=
_2dC.gif

ZLM: Not measured using IMO Cygnus LM area. Bortle 4 sky - suburban sky
where details of Milky Way are evident, but deteriorates to urban
skyglow at horizon.

NELM: Unable to measure. Approx. 4.2 based on 4.7 star on AAVSO Atlas
Chart 144. No IMO limiting magnitude areas in Sgr. Only stars in figure
of Sgr visible with averted vision v4.7 star on AAVSO Altas chart. Nova
was not visible from an urban 2.0 light polluted sky.

TELM: 11.0 based on TYC7393-00831-1 w/ 0.5 extinction. v10.95
TYC7392-00980-1 within 6 arcmins of nova was not visible.

Extinction coefficient applied: 0.55 (AAVSO Average Summer for 2
kilometer above sea level).

While you are there - other enjoyable objects in the immediate
vicinity:

1) HD169377 (8.4) and HD169337 (7.6), the optical double between del
Sgr and HD169586 are both listed by Cartes du Ciel and Simbad as each
being a double of about 6" separation. (Using 20x70 binos, I did not
split either of these doubles.)

2) Globular clusters near this area include NGC6624 (8.3, dia. 6'). Not
observed - NGC 6522 (8.6, dia. 5.6') and NGC 6528 (9.6, dia. 3.7').

3) For large aperature DSO observers, nearby faint planetary nebula on
the Sky 2000.0 chart include (not observed) PK003-6.1 (HD 317397, 11.8,
9x5", J181741.46-290819.2) and PK001-6.2 (HD 167362, 11.9, dia.
stellar, J181612.27-305208.1).=20

- Enjoy Canopus56