Bow shock crossing list at Mercury (from MESSENGER magnetic field data)

Version 2 (latest):  

This file contains a list of bow shock crossings at Mercury, identified from magnetic field data of the MESSENGER mission with 1 second resolution (not aberrated), (https://pds-ppi.igpp.ucla.edu/). 

For a pre-selection of intervals containing bow shock crossings, we use the list of Philpott (2020): "MESSENGER bowshock and magnetopause crossings", https://doi.org/10.5683/SP2/1U6FEO. There, the first and last crossings of the inbound/outbound orbit segments are listed (boundary numbers 1 and 2 for inbound, 7 and 8 for outbound segments). For the bow shock identification, an automatic detection algorithm is applied to these intervals, extended by 45 seconds in either direction.

The algorithm calculates running averages and variances of the magnetic field magnitude within adjacent 15 second intervals, separated by two seconds (gap interval). Whenever the ratio between the average magnetic fields exceed a threshold (default: 1.4), a bow shock crossing is selected. Should there be more than one ratio maximum within 10 seconds, then only the maximum is selected that corresponds to the minimal sum of the variances within the adjacent intervals. Crossings are classified with respect to detection quality depending on the ratios of the average magnetic fields and the corresponding variances. Details can be found in the algorithm script that is published alongside this file.

Columns of the list file: ['time', 'orbit_number', 'x_mso_km', 'y_mso_km', 'z_mso_km', 'jump_ratio', 'indicator']

'time': date and time in YYYY-MM-DD HH:mm:SS'orbit_number': orbit number (MESSENGER Mission)'x_mso_km': position (x-coordinate) in MSO coordinate system in km, not aberrated'y_mso_km': position (y-coordinate) in MSO coordinate system in km, not aberrated'z_mso_km': position (z-coordinate) in MSO coordinate system in km, not aberrated'in/out': inbound or outbound segment of the orbit (apoherm towards periherm or periherm towards apoherm)'jump_ratio': ratio of the average magnetic fields before and after selected crossings'indicator': 1, 2 or 3 (1: very clear crossings, high quality, 2: clear crossings, good quality, 3: unclear crossings, poor quality)

For further analysis it is recommended to only use the crossings with the indicators 1 and 2.The uncertainty in the determination of the times is +/- 2 seconds. 

Number of analyzed orbits: 3982Number of total crossings found: 13502Number of crossings with indicator 1 (very clear crossings, best quality): 1765Number of crossings with indicator 2 (clear crossings, good quality): 5027Number of crossings with indicator 3 (unclear crossings, poor quality): 6710

Version 1: 

This file contains a list of bow shock crossings at Mercury, identified from magnetic field data of the MESSENGER mission with 1 second resolution (not aberrated), (https://pds-ppi.igpp.ucla.edu/). 

For a pre-selection of intervals containing bow shock crossings, we use the list of Philpott (2020): "MESSENGER bowshock and magnetopause crossings", https://doi.org/10.5683/SP2/1U6FEO. There, the first and last crossings of the inbound/outbound orbit segments are listed (boundary numbers 1 and 2 for inbound, 7 and 8 for outbound segments). For the bow shock identification, an automatic detection algorithm is applied to these intervals, extended by 15 seconds in either direction.

The algorithm calculates running averages and variances of the magnetic field magnitude within adjacent 15 second intervals, separated by two seconds (gap interval). Whenever the ratio between the average magnetic fields exceed a threshold (default: 1.4), a bow shock crossing is selected. Should there be more than one ratio maximum within 10 seconds, then only the maximum is selected that corresponds to the minimal sum of the variances within the adjacent intervals. Crossings are classified with respect to detection quality depending on the ratios of the average magnetic fields and the corresponding variances. Details can be found in the algorithm script that is published alongside this file.

Columns of the list file: ['time', 'orbit_number', 'x_mso_km', 'y_mso_km', 'z_mso_km', 'in/out', 'jump_ratio', 'indicator']

'time': date and time in YYYY-MM-DD HH:mm:SS'orbit_number': orbit number (MESSENGER Mission)'x_mso_km': position (x-coordinate) in MSO coordinate system in km, not aberrated'y_mso_km': position (y-coordinate) in MSO coordinate system in km, not aberrated'z_mso_km': position (z-coordinate) in MSO coordinate system in km, not aberrated'in/out': inbound or outbound segment of the orbit (apoherm towards periherm or periherm towards apoherm)'jump_ratio': ratio of the average magnetic fields before and after selected crossings'indicator': 1, 2 or 3 (1: very clear crossings, high quality, 2: clear crossings, good quality, 3: unclear crossings, poor quality)

For further analysis it is recommended to only use the crossings with the indicators 1 and 2.The uncertainty in the determination of the times is +/- 2 seconds. 

Number of analyzed orbits: 3982Number of total crossings found: 65666Number of crossings with indicator 1 (very clear crossings, best quality): 4291Number of crossings with indicator 2 (clear crossings, good quality): 16652Number of crossings with indicator 3 (unclear crossings, poor quality): 44723