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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

4055 results found.

  1. LIGO/Virgo S230606d: Global MASTER-Net observations report
  2. LIGO/Virgo/KAGRA S230606d: Identification of a GW compact binary merger candidate
  3. LIGO/Virgo/KAGRA S230605o: Updated Sky localization
  4. IceCube-230603A: Upper limits from a search for additional neutrino events in IceCube
  5. LIGO/Virgo/KAGRA S230601bf: Updated Sky localization
  6. LIGO/Virgo/KAGRA S230605o: Identification of a GW compact binary merger candidate
  7. LIGO/Virgo S230605o: Global MASTER-Net observations report
  8. LIGO/Virgo S230604z: Global MASTER-Net observations report
  9. LIGO/Virgo S230603aa: Global MASTER-Net observations report
  10. LIGO/Virgo S230602ap: Global MASTER-Net observations report
  11. LIGO/Virgo/KAGRA S230518h: Upper limits from a two-week IceCube neutrino search
  12. LIGO/Virgo S230601bf: Global MASTER-Net observations report
  13. LIGO/Virgo/KAGRA S230601bf: Identification of a GW compact binary merger candidate
  14. LIGO/Virgo S230531f: Global MASTER-Net observations report
  15. LIGO/Virgo/KAGRA S230529ay: Zwicky Transient Facility observations
  16. LIGO/Virgo/KAGRA S230528a: Zwicky Transient Facility observations
  17. LIGO/Virgo/KAGRA S230527ch: Zwicky Transient Facility observations
  18. LIGO/Virgo/KAGRA S230529ay: Upper limits from CALET observations.
  19. LIGO/Virgo/KAGRA S230529ay: AstroSat CZTI non-detection and upper limits
  20. LIGO/Virgo S230529ay: Global MASTER-Net observations report
  21. LIGO/Virgo/KAGRA S230529ay: upper limits from AGILE/MCAL
  22. LIGO/Virgo/KAGRA S230529ay: Coverage and upper limits from MAXI/GSC observations
  23. LIGO/Virgo/KAGRA S230529ay: Upper limits from Fermi-GBM Observations
  24. LIGO/Virgo/KAGRA S230529ay: Updated Sky localization and EM Bright Classification
  25. LIGO/Virgo/KAGRA S230529ay: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  26. LIGO/Virgo/KAGRA S230529ay: Identification of a GW compact binary merger candidate
  27. LIGO/Virgo S230529p: Global MASTER-Net observations report
  28. LIGO/Virgo S230525a: Global MASTER-Net observations report
  29. LIGO/Virgo/KAGRA S230518h: Updated Sky localization
  30. LIGO/Virgo/KAGRA S230520ae: Updated Sky localization
  31. LIGO/Virgo/KAGRA S230518h: Upper limits from Glowbug gamma-ray observations
  32. LIGO/Virgo/KAGRA S230518h: TESS observations of the localization region
  33. LIGO/Virgo/KAGRA S230518h: No transient candidates in CALET observations
  34. LIGO/Virgo/KAGRA S230524x: Retraction of GW compact binary merger candidate
  35. LIGO/Virgo S230524b: Global MASTER-Net observations report
  36. LIGO/Virgo/KAGRA S230521k: MASTER new OT discovery
  37. LIGO/Virgo/KAGRA S230521k: Additional candidates from Zwicky Transient Facility
  38. LIGO/Virgo S230522n: Global MASTER-Net observations report
  39. LIGO/Virgo S230522a: Global MASTER-Net observations report
  40. LIGO/Virgo/KAGRA S230522n: Upper limits from IceCube neutrino search
  41. LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for MeerLICHT candidates: AT2023ixg and AT2023iyb
  42. LIGO/Virgo/KAGRA S230522a: 2 counterpart neutrino candidates from IceCube neutrino searches
  43. LIGO/Virgo S230521k: Global MASTER-Net observations report
  44. LIGO/Virgo/KAGRA S230521k: Zwicky Transient Facility observations
  45. LIGO/Virgo S230520ae: Global MASTER-Net observations report
  46. LIGO/Virgo/KAGRA S230520ae: Identification of a GW compact binary merger candidate: End-to-End Test
  47. LIGO/Virgo/KAGRA S230520ae: Upper limits from IceCube neutrino search
  48. LIGO/Virgo/KAGRA S230518h: ATCA follow-up of candidate counterparts
  49. LIGO/Virgo/KAGRA S230518h: GECKO tiling observations with KMTNet
  50. LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for Swope candidates: SSS23a, SSS23b and SSS23c
  51. LIGO/Virgo/KAGRA S230518h: ATLAS observations of the skymap
  52. LIGO/Virgo/KAGRA S230518h: Swope Search and Candidate Counterpart Identification
  53. LIGO/Virgo/KAGRA S230518h: Upper limits from Konus-Wind observations
  54. LIGO/Virgo S230518h: AGILE/MCAL observations
  55. LIGO/Virgo S230518h: Swift XRT observations, 8 X-ray sources
  56. LIGO/Virgo/KAGRA S230518h: Coverage and upper limits from MAXI/GSC observations
  57. LIGO/Virgo/Kagra S230518h: NED Galaxies in the Localization Volume
  58. LIGO/Virgo/KAGRA S230518h: AstroSat CZTI non-detection and upper limits
  59. LIGO/Virgo/KAGRA S230518h: Upper limits from Fermi-GBM Observations
  60. LIGO/Virgo S230518h: Global MASTER-Net observations report
  61. LIGO/Virgo/KAGRA S230518h: Updated Sky localization and EM Bright Classification
  62. LIGO/Virgo S230518h: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  63. LIGO/Virgo S230518h: Upper limits from IceCube neutrino search
  64. LIGO/Virgo/KAGRA S230518h: Identification of a GW compact binary merger candidate
  65. IceCube-230511A: Upper limits from a search for additional neutrino events in IceCube
  66. IceCube-230506A: Upper limits from a search for additional neutrino events in IceCube
  67. GRB 230423A: Swift/UVOT Upper Limits
  68. New GCN Circulars Portal for Rapid Communications on Astronomical Transients is Online
  69. GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
  70. GRB 221215A: Swift/BAT-GUANO arcminute localization
  71. GRB 221206B: Swift/BAT-GUANO candidate arcminute localization
  72. LIGO-Virgo-KAGRA and GEO600 statement on GRB 221009A
  73. IPN triangulation of GRB 220927A (long)
  74. GRB 220909A: Swift/BAT-GUANO candidate arcminute localization
  75. IPN triangulation of GRB 220903A (long)
  76. GRB 220831A: Swift/BAT-GUANO localization of a short burst
  77. Introducing new GCN Kafka broker and web site for transient alerts, https://gcn.nasa.gov
  78. GRB 220710A: Swift/BAT-GUANO arcminute localization
  79. IPN triangulation of GRB 220711C (short)
  80. GRB 220708B: Swift/BAT-GUANO arcminute localization
  81. GRB 220606B: Swift/BAT-GUANO candidate arcminute localization of a short burst
  82. IPN triangulation of GRB 220601A (long)
  83. Fermi-GBM will trial new SAA regions from Tuesday June 7th
  84. IPN triangulation of GRB 220524B
  85. IPN triangulation of GRB 220524A
  86. IPN triangulation of GRB 220521B
  87. IPN triangulation of GRB 220519A
  88. GRB 220514A: MITSuME Akeno optical observation
  89. GRB 220511A: Swift/BAT-GUANO arcminute localization
  90. IPN triangulation of GRB 220411A
  91. IPN triangulation of short/soft GRB 220406A
  92. GRB 220310C: Swift/BAT-GUANO candidate arcminute localization
  93. IPN triangulation of GRB 220308A (long / very bright)
  94. IPN triangulation of GRB 220222A
  95. GCN Circ.draft on GRB 220222A
  96. ZTF22aabjpxh/AT2022cva: NICER X-ray detection is consistent with a GRB afterglow
  97. IPN triangulation of GRB 220219B (consistent with ZTF22aabjpxh/AT2022cva)
  98. ZTF22aaajecp/AT2022cmc: NICER X-ray detection
  99. IPN triangulation of GRB 220211A (short)
  100. IPN triangulation of a bright burst from SGR 1935+2154

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