the CCD simulator
Make all measurements in a box of dimension 10×10 pixels.
For this assignment you will be making measurements via a simulation that has 4 different kinds of observing conditions (the conditions are unknown to you). These observing conditions have a big effect the kinds of stars that can be detected. In some cases, you will be unable to detect all of the stars.
For each of the four cases referenced below (and in your worksheet):
1 Determine the minimum exposure time required to believe that you can even “see” the star, using just your eye, with your virtual detector.
2 Determine the minimum exposure time so that the difference between the numbers in the green box labelled mean and red box labelled mean is approximately in the range 50 – 100. Remember, the star is centered in the green box while the detector background (e.g. the brightness of the virtual night sky in each case of the simulation) is registered in the red box.
Note that not all cases will produce a solution. You need to think about why that particular observing situation may be failing to detect the star at the level of 50-100 net counts.
Before starting it will be useful to watch this tutorial:
From this exercise it should be apparent to you that for any given exposure of the sky with any given telescope plus detector there will be many stars that are simply too faint to register on the detector and different detectors will require different amounts of exposure time to produce similar quality data (i.e. in this case 50- 100 net counts as the detection).
Download the blackbody simulator for this part
This simulator will reproduce the blackbody spectrum as a function of temperature. The X-axis is wavelength increasing to the right (decreasing energy per photon). The Y-axis is the amount of energy emitted at that wavelength. Clicking anywhere on the graph will indicate the wavelength (value of the X-axis) at location of the cursor. This is useful when you need to identify the wavelength of the peak emission. A background corresponding to the optical spectrum is superposed on the blackbody curve to ease in identification of color. That represents the wavelenght limits of human vision. At the long wavelength end, our vision dies out around 8000 angstroms as our eyes, compared to nocturnal predators, are not sensitive to infrared radiation. Light with wavelength shorter than about 3200 angstroms does not penetrate our our atmosphere. This is where the ultraviolet region of the electromagnetic spectrum begins.
As you change the temperature (T) you will see the curve changing but you will also see the numercial values in the B-V V-R U-B and T fields changing. For this exercise we will only care about the values in the T and B-V fields.
Answer the following questions in the worksheet for this assignment.
3 Set the temperature to approximately 8000 by using the slider bar (note the arrow keys on your keyboard can be used for fine temperature adjustment. What is the wavelength of the peak emission?
4 Now set the temperature to approximately 4000. What is the wavelength of the peak emission?
5 What is the ratio of the two wavelengths? (a ratio is two numbers divided by each other). Is this ratio what you expect? Explain why or why not.
6 What color would a star appear to be which has a temperature of 7000?
7 What color would a star appear to be which has a temperature of 4500?
Now click on the box that says “Draw Limits of Integration” -the white lines that appear there represent filter band passes of standard astronomical filters. To measure stellar temperatures, astronomers put filters in front of their digital cameras and measure the flux ratio between the two filters. For B (blue) and V (visual or green) this ratio is encoded as the index value B-V. The lower that number, the hotter the star (more flux is emitted in the B filter than the V filter. A value of B-V = 0.5 means that approximately the same amount of energy is emitted in the blue filter as the green filter.
8 What temperature produces a B-V value of 0.5?
9 Suppose that I can measure B-V to an accuracy of 10% (.1 in B-V). For the case of B-V = 0.5, what percentage change in temperature produces this 10% change in B-V? (i.e. B-V moves to 0.6 or 0.4 when you change the temperature)
10 Set T to 15000. At this temperature, what temperature change is required to change B-V by +/- 0.1?
11 Explain why B-V loses temperature sensitivity for these hot stars.
12 What kind of observations would you need to do perform in order to accurately measure the temperatures of very hot stars?
ORDER THIS ESSAY HERE NOW AND GET A DISCOUNT !!!
Our Service Charter
Excellent Quality / 100% Plagiarism-FreeWe employ a number of measures to ensure top quality essays. The papers go through a system of quality control prior to delivery. We run plagiarism checks on each paper to ensure that they will be 100% plagiarism-free. So, only clean copies hit customers’ emails. We also never resell the papers completed by our writers. So, once it is checked using a plagiarism checker, the paper will be unique. Speaking of the academic writing standards, we will stick to the assignment brief given by the customer and assign the perfect writer. By saying “the perfect writer” we mean the one having an academic degree in the customer’s study field and positive feedback from other customers.
Free RevisionsWe keep the quality bar of all papers high. But in case you need some extra brilliance to the paper, here’s what to do. First of all, you can choose a top writer. It means that we will assign an expert with a degree in your subject. And secondly, you can rely on our editing services. Our editors will revise your papers, checking whether or not they comply with high standards of academic writing. In addition, editing entails adjusting content if it’s off the topic, adding more sources, refining the language style, and making sure the referencing style is followed.
Confidentiality / 100% No DisclosureWe make sure that clients’ personal data remains confidential and is not exploited for any purposes beyond those related to our services. We only ask you to provide us with the information that is required to produce the paper according to your writing needs. Please note that the payment info is protected as well. Feel free to refer to the support team for more information about our payment methods. The fact that you used our service is kept secret due to the advanced security standards. So, you can be sure that no one will find out that you got a paper from our writing service.
Money Back GuaranteeIf the writer doesn’t address all the questions on your assignment brief or the delivered paper appears to be off the topic, you can ask for a refund. Or, if it is applicable, you can opt in for free revision within 14-30 days, depending on your paper’s length. The revision or refund request should be sent within 14 days after delivery. The customer gets 100% money-back in case they haven't downloaded the paper. All approved refunds will be returned to the customer’s credit card or Bonus Balance in a form of store credit. Take a note that we will send an extra compensation if the customers goes with a store credit.
24/7 Customer SupportWe have a support team working 24/7 ready to give your issue concerning the order their immediate attention. If you have any questions about the ordering process, communication with the writer, payment options, feel free to join live chat. Be sure to get a fast response. They can also give you the exact price quote, taking into account the timing, desired academic level of the paper, and the number of pages.