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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"

6791 results found.

  1. GRB 230728A: Swift-XRT refined Analysis
  2. Fermi-LAT gamma-ray observations of IceCube-230725A
  3. Fermi-LAT gamma-ray observations of IceCube-230724A
  4. GRB 230723B: Fermi GBM observation
  5. GRB 230723B: Swift-XRT refined Analysis
  6. Swift-XRT position for GRB 230723B
  7. GRB 230709C: Fermi GBM Detection
  8. GRB 230707B: Fermi GBM Observation
  9. IceCube-230707A: No candidates detected by Swift-XRT
  10. Fermi-LAT gamma-ray observations of IceCube-230708A
  11. Fermi-LAT gamma-ray observations of IceCube-230707B
  12. Fermi-LAT gamma-ray observations of IceCube-230707A
  13. GRB 230707A: Swift-XRT observations
  14. GRB 230707A: Fermi GBM Detection
  15. ZTF23aaoohpy/AT2023lcr : HCT follow-up observations
  16. LIGO/Virgo/KAGRA S230627c: GECKO optical follow-up observations of host galaxy candidates and ZTF23aaptsuy/AT2023lxu
  17. GRB 230628E: Swift-XRT refined Analysis
  18. LIGO/Virgo/KAGRA S230527c: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  19. GRB230626A: Fermi GBM Detection
  20. GRB 230623A: Swift-XRT observations
  21. INTEGRAL upper limit on any GRB associated with ZTF23aaoohpy/AT2023lcr
  22. ZTF23aaoohpy/AT2023lcr: further SAO RAS observations
  23. GRB 230622A: Swift-XRT refined Analysis
  24. ZTF23aaoohpy/AT2023lcr: SAO RAS observations
  25. ZTF23aaoohpy (AT2023lcr/ATLAS23msn): Upper limits from Konus-Wind observations
  26. AT2023lcr (ATLAS23msn/ZTF23aaoohpy): Kinder observations with Lulin observatory and a probable plateau in the g-band light curve
  27. ZTF23aaoohpy/AT2023lcr: GROWTH-India Telescope follow-up observations
  28. GRB 230618A: Swift-XRT refined Analysis
  29. GRB 230616A: Swift-XRT observations
  30. LIGO/Virgo/KAGRA S230615az: GROWTH-India candidates
  31. GRB 230614B: Fermi GBM Observation
  32. GRB 230614C: Fermi GBM Detection
  33. ZTF23aamxeqf/AT2023jxk: 1.3m DFOT Optical upper limit
  34. GRB 230506B: Chandra localization of the X-ray afterglow
  35. GRB 230606A: Fermi GBM Observation
  36. GRB 230606A: Swift-XRT refined Analysis
  37. Fermi-LAT gamma-ray observations of IceCube-230603A
  38. LIGO/Virgo/KAGRA S230529ay: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  39. Alert from the HAWC Burst Monitor HAWC-230527A
  40. Fermi-LAT gamma-ray observations of IceCube-230524A
  41. GRB 230525A: Fermi GBM Detection
  42. GRB 230524A: Fermi GBM Observation
  43. GRB 230518A: Fermi GBM Observation
  44. LIGO/Virgo/KAGRA S230518h: Upper limits from Konus-Wind observations
  45. LIGO/Virgo S230518h: AGILE/MCAL observations
  46. LIGO/Virgo S230518h: Swift XRT observations, 8 X-ray sources
  47. LIGO/Virgo S230518h: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  48. GRB 230513A: Zwicky Transient Facility continuous observations of a Fermi Short GRB (Trigger 705709044)
  49. GRB 230510B: Fermi GBM detection
  50. GRB 230513A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705709044)
  51. Fermi-LAT gamma-ray observations of IceCube-230511A
  52. GRB 230512A: Swift-XRT observations
  53. GRB 230512A: GIT optical follow-up ZTF candidates
  54. GRB 230512A: Fermi GBM detection
  55. GRB 230512A: Fermi-LAT detection
  56. GRB 230510A: GIT optical upper limits
  57. GRB 230510A: Fermi GBM detection
  58. GRB 230506B: Fermi GBM detection
  59. GRB 230510A: Swift-XRT refined Analysis
  60. GRB 230506C: Fermi GBM detection
  61. GRB 230506C: SAO RAS optical observations
  62. Fermi-LAT gamma-ray observations of IceCube-230506A
  63. GRB 230506C: Swift-XRT refined Analysis
  64. GRB 230506C: Swift/UVOT Upper Limits
  65. GRB 230506B: Swift-XRT refined Analysis
  66. GRB 230506C: Swift-XRT analysis
  67. GRB 230430A: Fermi GBM observation
  68. GRB 230427A: TSHAO, SAO RAS, AbAO optical upper limit
  69. GRB 230427A: Swift-XRT refined Analysis
  70. GRB 230427A: GIT optical upper limit
  71. GRB 230426A: Fermi GBM Detection
  72. GRB 230423A: Swift-XRT refined Analysis
  73. GRB 230421A: Fermi GBM observation
  74. GRB 230420A: Swift-XRT refined Analysis
  75. GRB 230420A: NOT optical afterglow confirmation
  76. GRB 230402A: Fermi GBM detection
  77. GRB 230418A: Fermi GBM Observation
  78. GRB 230402A: Fermi-LAT detection
  79. Fermi-LAT gamma-ray observations of IceCube-230416A
  80. GRB 230415A: Fermi GBM detection
  81. GRB 230414B: 3.6m DOT Optical observations, slow decay at early epochs
  82. GRB 230307A: iTelescope optical upper limit (likely)
  83. GRB 230414B: Lulin 40cm-SLT optical limit
  84. GRB 230414B: Swift-XRT refined Analysis
  85. GRB 230414B: 1.3m DFOT Optical observations
  86. GRB 230328B: redshift lower limit estimating
  87. GRB 230409B: Swift-XRT refined Analysis
  88. Fermi-LAT gamma-ray observations of IceCube-230405A
  89. GRB 230405B: Swift-XRT refined Analysis
  90. GRB 230405B: Fermi GBM Observation
  91. GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
  92. Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
  93. GRB 230307A: Chandra late-time detection of the X-ray afterglow
  94. GRB 230328B: 3.6m DOT multiband optical observation
  95. GRB 230328B: Swift-XRT refined Analysis
  96. GRB 230328B: Fermi GBM observation
  97. GRB 230325A: Swift-XRT refined Analysis
  98. GRB 230320B: Fermi GBM Observation
  99. GRB 230322B: Swift-XRT refined Analysis
  100. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow

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