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Updates based on APW

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Allen Downey
2020-10-12 14:39:09 -04:00
parent e0bd4b733c
commit 89b2b36895
2 changed files with 43 additions and 60 deletions
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29
03_motion.ipynb
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@@ -528,16 +528,7 @@
"\n",
"Adjust these arguments until you think the figure shows the data most clearly.\n",
"\n",
"Note: Once you have made these changes, you might notice that the figure shows stripes with lower density of stars. These stripes are caused by..."
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"TODO: what are they caused by? Rudy's comments:\n",
"\n",
">The low density appearance of stars when going from one projection to another is bothersome. It potentially hints at some error in the transform, higher order terms, or something. We'll need to dig around some more. "
"Note: Once you have made these changes, you might notice that the figure shows stripes with lower density of stars. These stripes are caused by the way Gaia scans the sky, which [you can read about here](https://www.cosmos.esa.int/web/gaia/scanning-law). The dataset we are using, [Gaia Data Release 2](https://www.cosmos.esa.int/web/gaia/dr2), covers 22 months of observations; during this time, some parts of the sky were scanned more than others."
]
},
{
@@ -1277,9 +1268,21 @@
},
{
"cell_type": "code",
"execution_count": 37,
"execution_count": 1,
"metadata": {},
"outputs": [],
"outputs": [
{
"ename": "NameError",
"evalue": "name 'df' is not defined",
"output_type": "error",
"traceback": [
"\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
"\u001b[0;31mNameError\u001b[0m Traceback (most recent call last)",
"\u001b[0;32m<ipython-input-1-54c499b1f8d4>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m phi_mask = ((df['phi2'] > phi2_min) & \n\u001b[0m\u001b[1;32m 2\u001b[0m (df['phi2'] < phi2_max))\n",
"\u001b[0;31mNameError\u001b[0m: name 'df' is not defined"
]
}
],
"source": [
"phi_mask = ((df['phi2'] > phi2_min) & \n",
" (df['phi2'] < phi2_max))"
@@ -1386,8 +1389,6 @@
"source": [
"`xlim` and `ylim` set the bounds of the x and y axis, so we can zoom in on stars near (-8, 0), which is the proper motion we expect for stars in GD-1.\n",
"\n",
"TODO: Why do we expect that? And it is related to the arbitrary choice of velocity when we transformed coordinates?\n",
"\n",
"You might notice that our figure is less dense than the one in the paper. That's because we're using stars from a relatively small region. Their figure is based on a region about 10 times bigger.\n",
"\n",
"Soon we'll go back and select stars from a larger region. But first we'll use the proper motion data to identify stars likely to be in GD-1."

74
04_select.ipynb
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@@ -84,30 +84,7 @@
"cell_type": "code",
"execution_count": 2,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"--2020-10-05 09:18:27-- https://github.com/AllenDowney/AstronomicalData/raw/main/data/gd1_dataframe.hdf5\n",
"Resolving github.com (github.com)... 140.82.112.4\n",
"Connecting to github.com (github.com)|140.82.112.4|:443... connected.\n",
"HTTP request sent, awaiting response... 302 Found\n",
"Location: https://raw.githubusercontent.com/AllenDowney/AstronomicalData/main/data/gd1_dataframe.hdf5 [following]\n",
"--2020-10-05 09:18:28-- https://raw.githubusercontent.com/AllenDowney/AstronomicalData/main/data/gd1_dataframe.hdf5\n",
"Resolving raw.githubusercontent.com (raw.githubusercontent.com)... 151.101.116.133\n",
"Connecting to raw.githubusercontent.com (raw.githubusercontent.com)|151.101.116.133|:443... connected.\n",
"HTTP request sent, awaiting response... 200 OK\n",
"Length: 17220088 (16M) [application/octet-stream]\n",
"Saving to: ‘gd1_dataframe.hdf5’\n",
"\n",
"gd1_dataframe.hdf5 100%[===================>] 16.42M 7.19MB/s in 2.3s \n",
"\n",
"2020-10-05 09:18:30 (7.19 MB/s) - ‘gd1_dataframe.hdf5’ saved [17220088/17220088]\n",
"\n"
]
}
],
"outputs": [],
"source": [
"import os\n",
"\n",
@@ -139,11 +116,9 @@
"\n",
"It would be more efficient to use ADQL to select only the stars we need. That would also make it possible to download data covering a larger region of the sky.\n",
"\n",
"However, the selection we just did was based on proper motion in the `GD1Koposov10` frame. In order to do the same selection in ADQL, we have to translate these motions into ICRS.\n",
"However, the selection we did was based on proper motion in the `GD1Koposov10` frame. In order to do the same selection in ADQL, we have to translate these motions into ICRS.\n",
"\n",
"We'll start by creating a `GD1Koposov10` object that contains the corners of the rectangle we just selected in proper motion.\n",
"\n",
"But we also need to specify right ascension and declination. For those, we'll use a point in the center of the selected region."
"We'll start by creating a `GD1Koposov10` object that contains the corners of the rectangle we just selected in proper motion."
]
},
{
@@ -151,18 +126,6 @@
"execution_count": 4,
"metadata": {},
"outputs": [],
"source": [
"import astropy.units as u\n",
"\n",
"phi1 = [-50, -50, -50, -50] * u.deg\n",
"phi2 = [2, 2, 2, 2] * u.deg"
]
},
{
"cell_type": "code",
"execution_count": 5,
"metadata": {},
"outputs": [],
"source": [
"pm1_min = -8.9\n",
"pm1_max = -6.9\n",
@@ -170,14 +133,33 @@
"pm2_max = 1.0"
]
},
{
"cell_type": "code",
"execution_count": 5,
"metadata": {},
"outputs": [],
"source": [
"import astropy.units as u\n",
"\n",
"pm1_rect = [pm1_min, pm1_min, pm1_max, pm1_max] * u.mas/u.yr\n",
"pm2_rect = [pm2_min, pm2_max, pm2_max, pm2_min] * u.mas/u.yr"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"But we also need to specify right ascension and declination. For those, we'll use a point in the center of the selected region."
]
},
{
"cell_type": "code",
"execution_count": 6,
"metadata": {},
"outputs": [],
"source": [
"pm1_rect = [pm1_min, pm1_min, pm1_max, pm1_max] * u.mas/u.yr\n",
"pm2_rect = [pm2_min, pm2_max, pm2_max, pm2_min] * u.mas/u.yr"
"phi1 = [-50, -50, -50, -50] * u.deg\n",
"phi2 = [2, 2, 2, 2] * u.deg"
]
},
{
@@ -717,10 +699,10 @@
" parallax float64 mas Parallax 0\n",
" parallax_error float64 mas Standard error of parallax 0\n",
"radial_velocity float64 km / s Radial velocity 13885\n",
"Jobid: 1601903914183O\n",
"Jobid: 1602527538799O\n",
"Phase: COMPLETED\n",
"Owner: None\n",
"Output file: async_20201005091834.vot\n",
"Output file: async_20201012143219.vot\n",
"Results: None\n"
]
}
@@ -950,7 +932,7 @@
"name": "stdout",
"output_type": "stream",
"text": [
"-rw-rw-r-- 1 downey downey 1.4M Oct 5 09:19 gd1_candidates.hdf5\r\n"
"-rw-rw-r-- 1 downey downey 1.4M Oct 12 14:32 gd1_candidates.hdf5\r\n"
]
}
],
@@ -1002,7 +984,7 @@
"name": "stdout",
"output_type": "stream",
"text": [
"-rw-rw-r-- 1 downey downey 2.9M Oct 5 09:19 gd1_candidates.csv\r\n"
"-rw-rw-r-- 1 downey downey 2.9M Oct 12 14:32 gd1_candidates.csv\r\n"
]
}
],