Is there any report to suggest that the astrologers knew about the birth of Ibraaheem (peace be upon him) and warned Nimrood about him?

Firstly: 

The
scholars have divided knowledge of the stars into two categories: 

1.Astronomy

this
refers to knowledge of the names of stars, when and where they rise and set,
and how they may be used for the purposes of measuring time and for
navigation, and other visible things which observation and experience have
proven what each star could be used for (working out directions, measuring
the passage of time and so on). 

There
is nothing wrong with learning and teaching this type of knowledge, and
there is no evidence to suggest that it is forbidden or makrooh to study it.
In fact, in the Holy Qur’an there is evidence to suggest that it is
permissible and this knowledge is a blessing that Allah, may He be glorified
and exalted, has bestowed upon people, as Allah, may He be glorified and
exalted, says (interpretation of the meaning):

“It is He Who has set the stars
for you, so that you may guide your course with their help through the
darkness of the land and the sea. We have (indeed) explained in detail Our
Ayat (proofs, evidences, verses, lessons, signs, Revelations, etc.) for
people who know”

[al-An‘aam 6:97]

“It is He Who made the sun a
shining thing and the moon as a light and measured out its (their) stages,
that you might know the number of years and the reckoning. Allah did not
create this but in truth. He explains the Ayat (proofs, evidences, verses,
lessons, signs, revelations, etc.) in detail for people who have knowledge”

[Yoonus 10:5]. 

2.Astrology

this
refers to interpreting the locations and movements of the stars and the 
(supposed) influence they have on worldly developments and events such as
death, birth, epidemics, disasters, attaining happiness and other matters
for which there is no rational, empirical basis for connecting these
developments to the movements of heavenly bodies. Rather this is mere
conjecture and speculation for which there is no proof or evidence. 

This
is what the shar‘i evidence definitively forbids; it is haraam to learn it,
teach it or study it. 

Shaykh
al-Islam Ibn Taymiyah (may Allah have mercy on him) said: 

The
craft of astrology which seeks to establish the influence and impact of
heavenly bodies, and to find out about future earthly events or developments
on the basis of celestial events, and to make a connection between celestial
movements and earthly influence, is a prohibited craft according to the
Qur’an and Sunnah, and the consensus of the ummah. In fact it is forbidden
by all the Messengers to their communities.

Allah,
may He be exalted, says (interpretation of the meaning):

“and the magician will never be
successful, no matter whatever amount (of skill) he may attain”

[Ta-Ha 20:69]

“Have
you not seen those who were given a portion of the Scripture? They believe
in Jibt [sorcery] and Taghoot [evil]”

[an-Nisa’ 4:51].

‘Umar
and others said that Jibt (sorcery) refers to magic or witchcraft. 

Abu
Dawood narrated in his Sunan with a hasan isnaad from Qubaysah ibn
Mukhaariq that the Prophet (blessings and peace of Allah be upon him) said:
“Augury (observing omens in birds etc.), superstition and geomancy come
under the heading of jibt (magic).” 

If
geomancy, which is akin to astrology, comes under the heading of jibt
(magic), then how about astrology itself? That is because in geomancy they
refer to shapes on earth, because astrology is based on shapes in the
heavens.

 Ahmad, Abu Dawood, Ibn Maajah and others narrated with a saheeh isnaad from
Ibn ‘Abbaas that he said: “Whoever learns astrology learns a branch of
magic; the more he learns (of the former) the more he learns (of the
latter).” The Messenger of Allah (blessings and peace of Allah be upon him)
clearly stated that astrology comes under the same heading as magic. Allah,
may He be exalted, says (interpretation of the meaning):

“and the magician will never be
successful, no matter whatever amount (of skill) he may attain”

[Ta-Ha 20:69].

And
this is how it really is. From studying the situation of astrologers, we see
that they never prosper either in this world or in the hereafter. 

Ahmad,
and Muslim in his Saheeh, narrated from Safiyyah bint ‘Ubayd, from
one of the wives of the Prophet (blessings and peace of Allah be upon him),
from the Prophet (blessings and peace of Allah be upon him) that he said:
“Whoever goes to a fortune teller and asks him about something, no prayer
will be accepted from him for forty days.” The astrologer is the same as the
fortune teller according to some of the scholars; according to others he
comes under the same category. If this is the case with regard to the one
who asks, then how about the one who is asked? 

He
also narrated in his Saheeh that Mu‘aawiyah ibn al-Hakam as-Sulami
said: I said: O Messenger of Allah, there are some men among us who go to
soothsayers. He said: “Do not go to them.” 

The
Prophet (blessings and peace of Allah be upon him) forbade going to
soothsayers, and astrologers are the same as soothsayers according to
al-Khattaabi and other scholars, and this was also narrated from the Arabs.
According to others, they come under the same category as soothsayers and
are worse than them. 

More
than one of the scholars has narrated that there is consensus on the
prohibition of astrology, such as al-Baghawi, al-Qaadi ‘Iyaad and others. 

In
as-Saheehayn it is narrated from Zayd ibn Khaalid al-Juhani that he
said: The Messenger of Allah (blessings and peace of Allah be upon him) led
us in praying Fajr at al-Hudaybiyah, after it had rained at night. When he
finished, he turned to the people and said: “Do you know what your Lord
said?” They said: Allah and His Messenger know best. He said: “He said:
‘This morning some of My slaves believe in Me and some disbelieve. As for
the one who said, we got rain by the bounty and mercy of Allah, he is a
believer in Me and a disbeliever in the stars. But as for the one who said,
We got rain by virtue of such and such a star, he is a disbeliever in Me and
a believer in the stars.’” 

Leading astrologers of the earlier and later generations have admitted that
in the case of the believers who worship Allah and turn to Him in
supplication, Allah removed from them – by virtue of the blessing of their
worship, supplication and trust in Allah – that which the astrologers said
on the basis of their astrological calculations would inevitably befall
them. They have also admitted that those who worship Allah, call upon Him
and put their trust in Him will be given reward in this world and in the
hereafter that no astrological power could ever bring them. 

Who has made the best of this world and the Hereafter in
following the Messengers, and has made the best nation those who enjoin what
is good and forbid what is evil.

End
quote from Majmoo‘ al-Fataawa, 35/192-196 

Secondly: 

However, we do not deny that some of what the astrologer says about future
events may sometimes be correct and may sometimes happen as he foretold; but
that does not mean that the path he is following is valid. Rather what he
happens to get right is baseless and comes about by pure coincidence. What
he gets right is very little in comparison to the lies that accompany it. 

Do you
not see that the Prophet (blessings and peace of Allah be upon him) has told
us that the jinn who eavesdrop (on the angels) may hear something of what
the angels talk about of future events, and the jinni may send down what he
has heard to the soothsayer on earth, or the jinni may be burned before he
can do that? Yet despite that, soothsaying is a major sin, because it deals
with matters of the unseen without any shar‘i basis. 

It was
narrated from ‘Aa’ishah (may Allah be pleased with her), the wife of the
Prophet (blessings and peace of Allah be upon him) that she heard the
Messenger of Allah (blessings and peace of Allah be upon him) say: 

“The
angels come down in the clouds and discuss matters that have been decreed in
heaven, and the devils may eavesdrop and hear it, then they convey it to the
soothsayers, and they tell along with it one hundred lies that they have
fabricated by themselves.”

Narrated by al-Bukhaari, no. 3210 

Hence
al-Qaadi ‘Iyaad (may Allah have mercy on him) said: 

Allah
may create in this type – meaning the astrologers – some kind of power, but
their lies are what predominates. End quote. 

Quoted
from Sharh an-Nawawi ‘ala Muslim, 14/223 

Shaykh
Ibn Baaz (may Allah have mercy on him) said: 

It may
so happen that the divine decree is in accordance with a person’s need, so
the poor man thinks that it is because of this astrologer, or because of
this soothsayer, that this thing happened. Or it may be that a person
prescribes a regular remedy other than what the astrologer claims, and that
the person who prescribes it knows that it is good for this sickness, but
the sick person thinks that healing comes about only because of the
astrologers looking at the stars, and so on. The point is that if healing
occurs sometimes after going to soothsayers or astrologers or geomancers and
their ilk, that does not prove that their way is sound. The mushrikeen
themselves – who worship idols – may come to an idol and ask of it, then
what they wanted happens by Allah’s leave, as a coincidence and for reasons
known to Allah in His wisdom, or it may come about by means of the devils,
and thus becomes a trial and test. But it does not come from the idol,
because the idol did not do anything, and the jinni who is with him did not
do anything. Rather the divine decree may dictate that this sickness should
go away or this calamity should be alleviated after this poor man went to
the idol and asked of it or offered a sacrifice to it. Thus that comes about
as a test and trial in itself, without that being the result of any action
on the part of the magician, the idol, the jinn and so on. This made the
mushrikeen even more attached to their idols, and thus they worshipped them
instead of Allah. 

The
wise person should never be deceived by what happens at the hands of these
astrologers, soothsayers, fortune tellers or magicians; rather he must keep
away from them and not believe in them.

End
quote from Majmoo‘ Fataawa Ibn Baaz, 8/89-90 

Thirdly: 

Once
the above is clearly understood, there will be no confusion from a
scientific or shar‘i point of view about the story of the astrologers at the
time of Nimrood and Ibraaheem (peace be upon him), if the story is even
sound in the first place. It is not unlikely that the words of the
astrologers may have turned out to be correct, although lies are more
prevalent in their case and the type of knowledge they have is corrupt. 

Yet we
should point out that the story is not proven with any saheeh isnaad; rather
it was narrated by some of the historians as just a story with no real
proof. 

See:
al-Bidaayah wa’n-Nihaayah by Ibn Katheer, 1/200 

And
Allah knows best.