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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').
  1. Swift Trigger 1244778 is not a GRB
  2. Swift GRB240725.11: Global MASTER-Net observations report
  3. IceCube-240721A: Two candidates from the Zwicky Transient Facility
  4. GRB 240720A: Swift-BAT refined analysis
  5. IceCube-240721A: Upper limits from a search for additional neutrino events in IceCube
  6. Fermi trigger No 743418632: Global MASTER-Net observations report
  7. Fermi trigger No 743315411: Global MASTER-Net observations report
  8. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  9. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  10. Fermi trigger No 743345551: Global MASTER-Net observations report
  11. Fermi-LAT gamma-ray observations of IceCube-240721A
  12. Fermi Gamma-ray Burst Monitor trigger 743271526/240721680 is not a GRB
  13. Fermi trigger No 743219692: Global MASTER-Net observations report
  14. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  15. IceCube Alert 240721.68: Global MASTER-Net observations report
  16. Fermi Gamma-ray Burst Monitor trigger 743243582/240721356 (GRB 240721A) is not a GRB
  17. GRB 240720B: SVOM/GRM observation
  18. GRB 240721A: Fermi GBM Final Real-time Localization
  19. GRB 240720B: AstroSat CZTI detection of a short burst
  20. Fermi GRB 240720A: Global MASTER-Net observations report
  21. GRB 240720A: AstroSat CZTI detection
  22. GRB 240720A: Fermi GBM observation
  23. GRB 240720A: Swift detection of a burst
  24. Swift GRB240720.02: Global MASTER-Net observations report
  25. Konus-Wind detection of GRB 240718A
  26. GRB 240713A: SVOM/GRM observation
  27. Fermi GRB 240718A: Global MASTER-Net observations report
  28. LAT GRB240718.27: Global MASTER-Net observations report
  29. GRB 240718A: Fermi GBM Observation
  30. IceCube-Cascade 240714A: TRT optical observations on the EP/FXT positions
  31. GRB 240718A: Fermi-LAT Detection
  32. GRB 240718A: SVOM/GRM observation
  33. GRB 240718A: BALROG localization (Fermi Trigger 742976945 / GRB 240718270)
  34. GRB 240718A: Fermi GBM Final Real-time Localization
  35. GRB 240712A: Swift-BAT refined analysis
  36. GRB 240716A: GECAM-B detection of a long burst
  37. SVOM/GRM In-Flight Trigger of GRB 240716A
  38. IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT
  39. GRB 240713A: 2.2m CAHA optical limit
  40. Fermi-LAT gamma-ray observations of IceCube-cascade-240714A
  41. GRB 240715A: Swift/UVOT observations of the XRT sources.
  42. GRB 240715A: Swift-XRT observations
  43. GRB240713A: Swift/UVOT Upper LImits
  44. EP240708a: X-ray follow-up observations with Swift/XRT
  45. GRB 240715A: GECAM-C detection of a short burst
  46. Konus-Wind detection of GRB 240715A
  47. LIGO/Virgo/KAGRA S240716b: Updated Sky localization
  48. GRB 240713A: Swift-XRT observations
  49. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  50. GRB 240712A: Swift-XRT refined Analysis
  51. SVOM/GRM In-Flight Trigger of GRB 240715A
  52. GRB 240713A: LAST optical upper limit
  53. LIGO/Virgo/KAGRA S240716b: Identification of a GW compact binary merger candidate
  54. GRB 240715A: Swift ToO observations
  55. Fermi GRB 240715A: Global MASTER-Net observations report
  56. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  57. GRB 240715A: Fermi GBM Observation
  58. GRB 240712A ATCA radio observations
  59. GRB240715A: GRANDMA Optical Upper Limits
  60. IPN triangulation of GRB 240715A (short)
  61. GW s240422ed: Swift UVOT follow-up
  62. GRB 240712A: Swift/UVOT Upper Limits
  63. EP-WXT flaring star and the optical flaring activity during its decay phase
  64. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  65. The EP-WXT source triggered on July 14th is likely a flaring star
  66. GRB 240715A: Fermi GBM Final Real-time Localization
  67. GRB 240713A: Tiled Swift observations
  68. GRB 240713A: J-band upper limit from WINTER
  69. GRB 240713A: NOT optical upper limits on three EP/FXT candidates
  70. GRB 240713A: JinShan optical upper limits
  71. GRB 240713A: OHP/T120 optical upper limit
  72. GRB240713A: X-ray follow-up observation with EP-FXT (duplicate submission of GCN 36859)
  73. GRB240713A: X-ray follow-up observation with EP-FXT
  74. GRB 240713B: AstroSat CZTI detection of a long burst
  75. GRB240713A: Optical upper limit with Kinder observations
  76. Fermi Sub-threshold Observation of GRB240713A
  77. GRB240713A: TAROT and GRANDMA Observations of SVOM/ECLAIRs GRB240713A
  78. GRB240713A : The first probable GRB Located on-Board SVOM by ECLAIRs
  79. Fermi Gamma-ray Burst Monitor trigger 742413075/240711744 is not a GRB
  80. EP240708a: GSP optical upper limit
  81. GRB 240712A: Swift detection of a burst
  82. LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
  83. GRB 240711A: Fermi GBM Final Real-time Localization
  84. Fermi trigger No 742405878: Global MASTER-Net observations report
  85. LIGO/Virgo/KAGRA S240627by: Updated Sky localization and EM Bright Classification
  86. Fermi trigger No 742317942: Global MASTER-Net observations report
  87. EP240708a: KAIT optical upper limit
  88. Fermi GRB 240710A: Global MASTER-Net observations report
  89. GRB 240710A: Fermi GBM Final Real-time Localization
  90. EP240708a: NOT optical observations
  91. EP240708a: SVOM/C-GFT optical upper limit
  92. EP240708a: X-ray follow-up observations with EP/FXT and Swift/XRT
  93. EP240708a: Optical upper limits with Kinder observations
  94. EP240708a: EP-WXT detection of a fast X-ray transient
  95. LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources
  96. EP240703b: GSP optical upper limit
  97. Fermi Gamma-ray Burst Monitor trigger 741911057/240705933 is not a GRB
  98. GRB 240705A: Fermi GBM Final Real-time Localization
  99. EP240703b: TRT optical upper limits
  100. EP240703a: TRT further optical observation

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