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NGC 1964

NGC 1964 is a very distant and very bright spiral galaxy. In fact, it is calculated to be about 65 million light years away from the earth. The published physical size of the galaxy is 6.5 arcmin for the major axis, and 2.1 arcmin for the minor axis. These axis measurements correspond to a value of 123000 lightyears in the major axis, and 18800 lightyears for the minor axis. The galaxy is found in the constellation named “Lepus” which means hare. The constellation hare is located just below Orion's belt. Hare is known as the rabbit that “Orion the hunter” is hunting. NGC 1964 was discovered in 1784 by the famous astronomer William Herschel. While data has been collected and published on NGC 1964 little to no published studies has been done on the galaxy alone. In fact, there are no scholarly articles about this galaxy in the NASA’s database. NGC 1964 is unique galaxy because it is a very unstudied galaxy, most galaxies that are as bright and significant as NGC 1964 have had multiple studies and articles published. Although the galaxy might look like an elliptical galaxy from the picture above better pictures show that it is actually clearly a spiral galaxy with faint arms extending around the very bright center of the galaxy.

Above is a picture from the aladin viewing software. The picture from the software provides a clearer and more visible image than Calvin’s telescope had the ability to obtain for this project. As mentioned earlier NGC 1964 is a spiral galaxy meaning that is has a dense, and bright core with rotating arms spiraling around it. The galaxy is mostly yellow in color, from looking at the image from aladin small amounts of blue and red colors are visible. The fact that there are some blue stars in the galaxy means that they are very hot stars that do not have a very long life span, therefore they must have been formed relatively recently. The very bright, primarily yellow center of the galaxy comes from a large amount of bright, and older stars packed tightly together in the center of the galaxy. NGC 1964 is a spiral galaxy, but the arms are not very prominent. Bright pink colors in a galaxy would signify star-forming emission nebula, a lack of such colors in the spiral arms signifies that the star formation is calm. Meaning that there is not much star formation going on in the galaxy. In the image you can see some very bright and relatively large spots near the galaxy, but those are simply stars that are in the frame of the picture.

This image shows a screenshot of part of process of finding the physical size along the major axis. A process very similar to what is displayed in this picture was also used for the qualitative analysis of the brightness of the galaxy with respect to the distance from the center of the galaxy.

According to the Nasa Extragalactic Database the galaxy NGC 1946 is a mean distance of 19.900 megaparsecs away from earth. A distance of 19.9 Mpc corresponds to a distance of 6.419(10)^7 lightyears away from earth. When calculating the physical size of the galaxy the first process is taking measurements from MaxIm. In MaxIm a line was drawn across the major and minor axis as shown above, which gave a value of a certain amount of pixels. The amount of pixels was then related to arcseconds. The conversion is (pixels*1.32 = arseconds). Arcseconds were then converted to radians. The radians were then converted to light years by using the formula θ = l/d where theta is the value in radians, d is the distance that the galaxy is from earth, and l is the physical length of the galaxy. The final values that were calculated for the physical size was 88,465 lightyears for the major axis, and 27,762 lightyears for the minor axis. The measurement has a fairly large uncertainty, due to the fact that it is fairly difficult to find a definite point that the galaxy comes to an end.

An analysis of the relationship between the distance from the center of the galaxy and the luminosity was performed on NGC 1964. This type of analysis is interesting because it can help understanding just how tightly packed the galaxy is. The equation generated from this graph can predict with very good accuracy how luminous the galaxy will be and any distance from the center. The results are displayed on the graph as shown above. The results were obtained by using the graph function on MaxLm, after drawing a line through the major axis of the galaxy (similar to the process used to find the physical size) the data was obtained and exported to excel. The major axis was used because it provides the most accurate representation of what the galaxy is like without being effected by the angle of viewing. After editing the data in excel it was exported to Logger Pro, where it was analyzed and fitted to a specified curve fit. The fit that was used was I(r) = Io*exp(-r/Rs) + C. This equation was used because it is known by astronomers to do an accurate job of correlating distance from the center of a galaxy, and the luminosity at that point. Logger pro used the data to find a best fit equation of . Where r is the distance from the center of the galaxy (in pixels) and I(r) is the luminosity as a function of distance from the center. When the Rs value of 2.320(±0.1244) pixels is converted to kpc it yields a value (.2955±.0158) this is very close to a factor of 10 times smaller than the value of the milky way (3 kpc). That data shows that NGC 1964 is packed much tighter to the center than the milky way, with most all of the brightness coming from the core as the pictures reinforce. The final equation with tolerances and the Rs value converted to kpc is The correlation of the data and the best fit line has a very strong value of R=0.9754.

 

In order to create the final image of the observed galaxy data reduction was necessary. When data is delivered to from Calvin's telescope in Rehoboth NM. it is a series of shots with different filters. The point of data reduction is to reduce all of those different pictures with different pictures into one final color image. The first step in reducing the data with MaxIm is to make sure that there are not any extreme outliers in the pictures, if there is a picture that looks wrong or a satellite flies in front of the telescope that picture must be taken out. Next, from the images that are left they are compiled into a master bias. Only one master bias is made for all of the data. After creating the master bias, the next step is to create the dark bias. Along with the bias filters it was necessary to make a master flat file for each filter, this is where the bias filters come into effect. When making the master flat files MaxIm takes the data from the biases, and erases any pixels that are the same as the dark and bias. This process leaves behind only nonuniform illumination. After creating all three of the previous files we can now reduce the data filter by filter. The dark, master bias, and the appropriate master flat are all used to reduce the data. The newly reduced data was then saved and was later compiled and edited to give the most desirable image possible. After the file was compiled into one color image editing ensued to display the final image. The color combination that was found ideal was a balance of one red, 2 green, and 4 blue. This combination of color provided an image that had surrounding stars appearing white and clear in color. The color saturation was adjusted slightly to 120% in order to provide a more vivid picture. lastly the luminosity window was tightened up a small amount to the luminosity range of 920 to 1950.

References:

"NGC 1964." ned.ipac.caltech.eduNED. Accessed 26 Apr. 2017. <http://ned.ipac.caltech.edu/>

aladin software v9.0 <http://aladin.u-strasbg.fr/>

"Hare (constellation)." wikipediea, https://it.wikipedia.org/wiki/Lepre_(costellazione). Accessed 26 Apr. 2017. "Hare (constellation)"

"NGC 1964." Wikipedia, https://it.wikipedia.org/wiki/NGC_1964. Accessed 26 Apr. 2017. "NGC 1964"

Right Ascension (J2000) 05:33:21.7
Declination (J2000) -21:56:54
Filters used B (Blue), C (Clear), R (Red), V (Green)
Exposure time per filter B(300s), V(300s), R (300s),and C (60s)
Image dimension 795x567 pixels; 23.8x16.1 arcminutes
Date/time observed Febuary, 27,2017, 7:09 UT

 

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