Microlensing parallax

I am doing a little work in microlensing parallax between two observatories. First step: replicate others’ work! Here is my attempt to replicate Figure 1 of Henderson & Shvartzvald (2016).

And here is Figure 2:

Figure 3:

Here is a scatter plot of mu_rel for $D_l = 1$kpc and $D_s = 8.2$ kpc, with the bulge velocity distribution used for the lens:

Animation of the positions of Earth and Kepler, in 2022, projected onto the observer plane, pointing towards a source at the centre of the K2 superstamp:

Plot of theta for Kepler-Earth, over a year:

Using the same assumptions as H&S, here is their Figure 3 replicated:

Here is some work going beyond H&S Figure 3, using the samples from the actual observer ephemerides along with the Galactic model draws:

Here is Figure 4 replicated:

Here is Figure 6 replicated:

Here is a first attempt at characterising the type of lenses that Cleopatra will be sensitive to:

Here is a final set of relative sensitivity histograms for a 20cm and a 50cm primary mirror, for two different values of d_perp, two different min(Amax) values and two choices of minimum sampling:

Observation Planner

While there are any number of excellent software products available to help an observer plan an observing session, I was more interested in producing a single image that could give an idea of what objects were in prime viewing position.

Using astroplan, astropy, adjustText and jplephem, I have a first attempt done.

So far the code will plot out the maximum altitude of a set of objects, as seen from an observer’s position on Earth, as a function of the day of the year. I gave some indicative altitude curves for some objects, to get a sense of their position change across their maximum altitude. The small number at the start of each curve is the azimuth.

The input is currently one of the Messier and NGC catalogues, but any list of objects can be included as a csv file. The object needs to be resolvable via astropy’s SkyCoord call.

Maximum altitude of Messier objects, Auckland, NZ at UTC 1200 in 2022. Times of new moon are shown with dashed vertical lines.

Astrophotography observation planning

I’ve been having some fun using the astroplan library to predict when are the optimal times in the year to observe some deep sky objects. Here is a sky plot for M6 as seen from Auckland, New Zealand.

Sky plot of M6 as seen from Auckland, at local midnight on the first of each month, 2021.

The full sky plot is useful to me as half of my sky is blocked by either buildings or suffers extreme light pollution. The eastern sky is best for me. So this pushes me towards May/June for observations.

NJR Honours Projects for 2018

Here’s my list of Honours projects for 2018. If you are keen to do one of these, please email me or drop by to discuss.

1. University of Auckland Ground Station 1

The University’s first CubeSat mission is scheduled to fly late 2018. We have a ground station on top of the Physics building to communicate with satellites. This station requires final calibration and testing, and development of corresponding control and analysis software. This work will be done in conjunction with the Auckland Programme for Space Systems, using the new APSS laboratories on Symonds Street and the Department of Physics Electronics Laboratory. You will be working with students and staff in the Faculty of Engineering, as well as in the Faculty of Science. You will also assist in the preparation to communicate with the first APSS satellite mission via the Defence Technology Agency’s ground station, working with DTA staff to ensure a smooth connection between the DTA systems and the University network.

This will be of interest to you if:

  • you have a reasonable grasp of radio communications,
  • good electronics / lab skills,
  • good computer network skills,
  • excellent written and oral communication skills,
  • an interest in space system hardware.
Listen and track satellites and help us get ready for launch in 2018!

Listen and track satellites and help us get ready for launch in 2018!


2. Hauraki Gulf Space Observation Honours Projects

Coastal science is both complex and complicated. There is a lack of detailed information on the interaction between ocean and coast, the coastal ecology and the relationships between the coastal environment and life on and near the coast. Each of the following projects relates to an overall goal of imaging the Hauraki Gulf from space. These earth observation projects are multi-disciplinary and will be carried out in conjunction with the Department of Marine Science and the Department of Engineering Science in the Faculty of Engineering.

2a. Geosynchronous CubeSat Feasibility Study

For this project you will scope and design a small satellite system that is capable of imaging the Hauraki Gulf to a few metres resolution from a geosynchronous orbit. These image data will be used to measure coastal sea colour, elevation, turbidity and reflectance. You will need to investigate commercial off the shelf optics and imaging systems that can provide the necessary resolution, and can operate within the power, volume, mass and communication bandwidth budgets of a small satellite system bus. You will need a good grounding in optics, electronics and some signal processing. Experience in space systems is not required. You must have excellent written and oral communication skills as you will be required to interact with a range of individuals both across different University Faculties and Departments, as well as external hardware and service providers.

This will be of interest to you if:

  • you have an interest in space system mission design,
  • good electronics / optics skills,
  • familiarity with signal processing and data analysis,
  • excellent written and oral communication skills.

2b. Earth Observation Satellite Data Analysis

This project will require you to make a census of the available satellite imaging and radar data of the Hauraki Gulf. A number of existing satellite missions make their data freely available, such as ESA’s Sentinel optical and synthetic aperture radar satellites. You will investigate what sources of data are available, summarise basic meta data of each data source (e.g. how often images are taken, wavelengths, resolutions, etc). You will work with satellite imaging experts both in Auckland and at the Centre for Space Science Technology to identify modes of imaging that will provide the information required to address the science goals of the project — or identify a need for more imaging. You will also use existing analysis software to do preliminary data analysis for suitable datasets.

This will be of interest to you if:

  • you have an interest space-based data analysis,
  • very good programming skills,
  • familiarity with image analysis,
  • excellent written and oral communication skills.


3. Design a UV space telescope mission to detect intermediate mass black holes

Intermediate mass black holes are theorised to exist in our Galaxy. They are difficult to detect, however. One channel for discovery is by looking for tidal disruption flares (TDFs), wherein a companion to a black hole is disrupted the the gravitational distortion of the BH and emits bursts of radiation. These transient events are highly energetic, but emit most of the radiation in the UV, making ground-based observations only sensitive to the brightest events. This project will be to design a small satellite to make UV observations from space, in order to detect fainter TDFs. You will be working with colleagues at The University of Warsaw.

This will be of interest to you if:

  • you have an interest in space system mission design,
  • you have a good background in — or at least a strong interest in — astronomy or astrophysics,
  • good electronics / optics skills,
  • excellent written and oral communication skills.


4. Astronomical Seeing Measurements in the Greater Auckland Area.

One of the Department’s 40 cm Meade telescopes has been converted into a seeing monitor. Seeing is a measure of atmospheric turbulence. This project will involve the student making seeing observations at various sites in the Greater Auckland area, analysing the results and publishing these. The student will have to be comfortable working at night, and have a full driver’s licence. You will make seeing measurements using the dedicated software written for the instrument, as well as a commercial seeing analysis package and compare the results.

Use one of these!


This will be of interest to you if:

  • you have an interest in astronomy,
  • very good programming skills,
  • familiarity with image analysis,
  • excellent written and oral communication skills.


5. Multidimensional Dataset Visualisation with an Oculus Rift

This project will require the student to investigate multidimensional astronomical datasets using an Oculus Rift. Students should have a high level of programming ability. You will be using the iViz visualisation software from Virtualitics (no experience necessary).

This will be of interest to you if:

  • you have an interest in data analysis, and human-computer interaction,
  • excellent programming skills,
  • excellent written and oral communication skills.

Oculus Rift DK2


Microlensing 22 will be held in Auckland, January 2018


The next annual microlensing conference will be held in Auckland, New Zealand on January 25th to 28th, 2018. This announcement is so that you can save the dates in your calendar. The first full announcement will follow shortly.

This meeting is the 22nd in the series of international conferences on microlensing and will include topics such as:

  • Planet detection by microlensing from both ground and space,
  • Latest theoretical and observational advances,
  • Predictions and proposed answers to current challenges
  • Tensions in exoplanetary science and how microlensing can address these.

The SOC for Microlensing 22 is

Rachel Akeson (Caltech/IPAC)
Valerio Bozza (University of Salerno)
Scott Gaudi (The Ohio State University)
Calen Henderson (Caltech/IPAC)
Jessica Lu (University of California Berkeley)
David Nataf (Johns Hopkins University)
Nick Rattenbury (University of Auckland)
Rachel Street (Las Cumbres Observatory)
Takahiro Sumi (Osaka University)
Andrzej Udalski (Warsaw University)

We look forward to seeing you in Auckland!


The Microlensing 22 SOC