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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"

3028 results found.

  1. IceCube-201021A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  2. GRB 201020A: DOAO optical afterglow observations
  3. GRB 201020A: Fermi GBM observation
  4. GRB 201020A: Swift detection of a burst with an optical counterpart.
  5. GRB 201008A: Swift-XRT afterglow detection
  6. GRB 201016A: Fermi GBM detection
  7. GRB 201013A: TSHAO and AbAO optical observations, afterglow confirmation
  8. GRB 201013A: FRAM-ORM possible afterglow candidate
  9. IceCube-201007A: No candidate counterparts from the Zwicky Transient Facility
  10. GRB 201013A: Swift detection of a burst
  11. GRB 201008A: Swift-XRT observations
  12. Fermi trigger No 623470566: Global MASTER-Net observations report
  13. Fermi trigger No 623493962: Global MASTER-Net observations report
  14. IceCube-200926A: No candidate counterparts from the Zwicky Transient Facility
  15. IceCube-200929A: No significant detection in HAWC
  16. IceCube-200929A: No neutrino counterpart candidates in ANTARES search
  17. IceCube-200926B: No significant detection in HAWC
  18. IceCube-200926A: No Candidate Counterparts from the Zwicky Transient Facility
  19. IceCube Alert 200926.33: Global MASTER-Net observations report
  20. Fermi GRB 200925A: Global MASTER-Net observations report
  21. Fermi GRB 200924A: Global MASTER-Net observations report
  22. Fermi GRB 200923A: Global MASTER-Net observations report
  23. IceCube Alert 200921.80: Global MASTER-Net observations report
  24. GRB 200922A: Swift/UVOT Detection
  25. IceCube-200921A: no significant detection in HAWC observations
  26. Fermi GRB 200922B: Global MASTER-Net observations report
  27. GRB 200922A: LCO observations
  28. GRB 200920A: Fermi GBM Final Real-time Localization
  29. Fermi GRB 200919C: Global MASTER-Net observations report
  30. Fermi GRB 200919B: Global MASTER-Net observations report
  31. IceCube-200916A: Two Candidate Counterparts from the Zwicky Transient Facility
  32. IPN triangulation of GRB 200916B (short)
  33. IceCube Alert 200914.00: Global MASTER-Net observations report
  34. IPN triangulation of GRB 200907A (short)
  35. Fermi GRB 200908A: Global MASTER-Net observations report
  36. Fermi GRB 200907C: Global MASTER-Net observations report
  37. GRB 200906A: Nanshan/NEXT optical upper limit
  38. Fermi GRB 200903B: Global MASTER-Net observations report
  39. GRB 200901A: Fermi GBM observation
  40. GRB 200901A: Swift detection of a burst
  41. GRB 200829A: Koshka Zeiss-1000 optical observations
  42. Fermi trigger No 620402299: Global MASTER-Net observations report
  43. Zwicky Transient Facility discovery of ZTF20abtxwfx/AT2020sev, a fast optical transient and candidate afterglow
  44. IPN triangulation of GRB 200826B
  45. GRB200826A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 620108997)
  46. IPN triangulation of GRB 200815A (short)
  47. GRB 200819A: Kitab, TSHAO optical upper limit
  48. Fermi GRB 200817A: Global MASTER-Net observations report
  49. GRB 200817A: Fermi GBM Final Real-time Localization
  50. Fermi trigger No 619270776: Global MASTER-Net observations report
  51. Fermi GRB 200803A: Global MASTER-Net observations report
  52. Fermi GRB 200802A: Global MASTER-Net observations report
  53. GRB 200802A: Fermi GBM Final Real-time Localization
  54. Fermi GRB 200801A: Global MASTER-Net observations report
  55. Swift Detection of an SGR-like flare from AX J1846.4-0258
  56. Swift GRB200801.84: Global MASTER-Net observations report
  57. Fermi GRB 200716A: Global MASTER-Net observations report
  58. GRB 200716C: Swift detection of a burst with an optical counterpart
  59. Fermi GRB 200714D: Global MASTER-Net observations report
  60. Fermi GRB 200714A: Global MASTER-Net observations report
  61. Fermi trigger No 616370565: Global MASTER-Net observations report
  62. Update of alert from the HAWC Burst Monitor HAWC-200709A
  63. Fermi GRB 200705A: Global MASTER-Net observations report
  64. Trigger 980513: Swift detection of SGR Swift J1818.0-1607
  65. GRB 200630A: Swift detection of a burst
  66. Fermi GRB 200626A: Global MASTER-Net observations report
  67. IceCube-200620A: One Candidate Counterpart from the Zwicky Transient Facility
  68. LIGO/Virgo MS200618aq: Retraction of a test binary neutron star candidate
  69. Fermi trigger No 614103490: Global MASTER-Net observations report
  70. Baksan Neutrino Observatory Alert 200617.47: Global MASTER-Net observations report
  71. GRB 200616B: Fermi GBM Final Real-time Localization
  72. GRB 200615B: MAXI/GSC detection
  73. Baksan Neutrino Observatory Alert 200614.34: Global MASTER-Net observations report
  74. GRB 200614A: Fermi GBM Final Real-time Localization
  75. Swift GRB200612.19: Global MASTER-Net OT detection
  76. Swift GRB200612.19: Global MASTER-Net observations report
  77. Fermi GRB 200604A: Global MASTER-Net observations report
  78. Baksan Neutrino Observatory Alert 200603.12: Global MASTER-Net observations report
  79. GRB 200529A: MITSuME Akeno optical upper limits
  80. Fermi GRB 200601A: Global MASTER-Net observations report
  81. IceCube-200530A: Candidate Counterparts from the Zwicky Transient Facility
  82. Swift GRB 200528A: Global MASTER-Net observations report
  83. GRB 200524A: CrAO optical observations
  84. GRB 171205A: ATCA observations of late-time radio emission
  85. Fermi GRB 200522B: Global MASTER-Net observations report
  86. GRB 200522B: Fermi GBM Final Real-time Localization
  87. Fermi trigger No 611676654: Global MASTER-Net observations report
  88. GRB 200519A: Swift detection of a burst with an optical afterglow
  89. Fermi trigger No 611434353: Global MASTER-Net observations report
  90. GRB 200517A: MAXI/GSC detection
  91. GRB 200514B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 611140062) - More Candidates
  92. GRB 200514A: MITSuME Akeno optical upper limits
  93. GRB200514B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 611140062)
  94. IceCube-200512A: No Candidate Counterparts from the Zwicky Transient Facility
  95. Konus-Wind observation of SGR 1935+2154 activity on 2020 May 10
  96. GRB 200509A: Swift detection of a burst with a possible optical counterpart
  97. Insight-HXMT X-ray and hard X-ray upper limits to the radio burst detected by FAST from SGR 1935+2154
  98. Fermi GBM trigger 200429866/609886052 is not a GRB
  99. Konus-Wind observation of hard X-ray counterpart of the radio burst from SGR 1935+2154
  100. Konus-Wind observation of a very intense bursting activity of SGR 1935+2154

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